Updated 2011 September 23
The equations for the light curves of comets that are currently visible use only the raw observations and should give a reasonable prediction for the current brightness. If the comet has not yet been observed or has gone from view a correction for aperture is included, so that telescopic observers should expect the comet to be fainter than given by the equation. The correction is about 0.033 per centimetre. Values for the r parameter given in square brackets [ ] are assumed. The form of the light curve is either the standard m = H0 + 5 log d + K0 log r or the linear brightening m = H0 + 5 log d + L0 abs(t - T + D0) where T is the date of perihelion, t the present and D0 an offset, if L0 is +ve the comet brightens towards perihelion and if D0 is +ve the comet is brightest prior to perihelion.
Observations of individual comets are given below, but if you want to view the latest observations of all comets, here are the ones I've received recently in TA format (note that observations received in ICQ format are in the individual files only). All observation lists are given in ICQ format.
Full details of recently discovered objects will not appear until they are available on the CBAT web pages, which is usually a fortnight after the publication of the IAUC.
Brian Marsden notes on MPEC 2004-X73 [2004 December 14]
Although the orbits computed for the SOHO comets that are members of sungrazing groups other than Kreutz have hitherto necessarily been assumed to be parabolic, the low orbital inclinations and the indicated associations with meteor streams suggest that the members of the Marsden and Kracht groups, at least, are of short period (which still means that e is no smaller than 0.98). If so, it might now be the case that individual members can be recognized at more than one perihelion passage. Furthermore, the implied success in having at least one member survive perihelion passage would provide an obvious mechanism for the continued maintenance of these comet groups.Comet 1999 J6 was around 7th magnitude in the LASCO C3 and faded quite rapidly. This suggests that it would probably not be brighter than 13th magnitude during its close approach. It would have been very favourably placed for northern hemisphere observers on 1999 June 11/12 and 12/13, crossing across half the sky during this time and passing some 6 degrees from the pole.
It is eminently possible that C/2004 V9 is in fact identical with C/1999 J6 (cf. MPEC 2000-F30). To demonstrate this, the following represents a tentative linkage of the observations. Since there is a well-known inconsistency between the C3 and C2 observations, only the latter (i.e., those of the 1999 comet made on May 11.46257 UT and earlier and those of the 2004 comet on Nov. 8.35423 and earlier) have been used, the resulting residuals being very comparable to those of the individual parabolic solutions. It should also be noted that the object would have passed only 0.0091 AU from the moon and 0.0087 AU from the earth on 1999 June 12.22 and 12.31 UT, respectively.Epoch 1999 May 22.0 TT = JDT 2451320.5 T 1999 May 11.58356 TT MPC q 0.0491317 (2000.0) P Q n 0.17952782 Peri. 22.21043 -0.20252199 -0.87330037 a 3.1120618 Node 81.80049 +0.81764025 -0.39980558 e 0.9842125 Incl. 26.59424 +0.53893345 +0.27839172 P 5.49 Epoch 2004 Nov. 11.0 TT = JDT 2453320.5 T 2004 Nov. 8.56075 TT MPC q 0.0490617 (2000.0) P Q n 0.17940682 Peri. 22.31612 -0.20213975 -0.87355162 a 3.1134609 Node 81.67998 +0.81732637 -0.39954766 e 0.9842421 Incl. 26.58223 +0.53955270 +0.27797346 P 5.49Earlier computations, by both Brian Marsden and P. Chodas, Jet Propulsion Laboratory, had suggested linkages among C2 observations of Kracht Group comets, namely, the possibility that C/1999 M3 (MPEC 2002-E18) = C/2004 L10 (MPEC 2004-O05) and that C/1999 N6 (MPEC 2002-F03) = C/2004 J4 or C/2004 J18 (MPEC 2004-M71, 2004-N05).
For further information on the discovery of these objects see this year's SOHO discoveries.
The IAU Committee on Small Bodies Nomenclature has decided to name three comets as follows: C/1996 R3 (Lagerkvist), P/2003 A1 (LINEAR), P/2004 A1 (LONEOS). [IAUC 8430, 2004 November 6]
B. A. Skiff, Lowell Observatory, reports the discovery of a comet found on CCD images taken by himself on January 13.27 in the course of the LONEOS program with the 0.59-m Schmidt telescope. The LONEOS images showed stellar appearance, but the motion led Skiff to request that a pair of 5-min R-band CCD exposures be taken of the object by H. R. Miller at the Perkins 1.8-m reflector, and these images show a 3" well- condensed coma and a 12" tail in p.a. 290 deg. To get additional observations, the object's ephemeris was then posted on the NEO Confirmation Page, which resulted in CCD images taken by J. Young (Table Mountain, CA, 0.6-m reflector) on Jan. 13.5 UT that show a 4" coma with a very faint 10" tail in p.a. 262 deg. [IAUC 8267, 2004 January 13]
The comet was finally named in 2004 November.
The IAU Committee on Small Bodies Nomenclature has decided to name three comets as follows: C/1996 R3 (Lagerkvist), P/2003 A1 (LINEAR), P/2004 A1 (LONEOS). [IAUC 8430, 2004 November 6]
An apparently asteroidal object reported by the LINEAR project on January 29.16, and posted on the NEO Confirmation Page, has been reported by J. Young (from CCD exposures taken with the 0.6-m reflector at Table Mountain Observatory on Jan. 30.1 UT) to have a 3" round coma with a broad extension 4" long in p.a. 300-320 deg. [IAUC 8279, 2004 January 30]
Brian Marsden notes on MPEC 2004-S27 [2004 September 20] that
The "original" and "future" barycentric values of 1/a are +0.000270 and -0.000245 (+/- 0.000224) AU^-1, respectively.The "original" value suggests that this is not a "new" comet.
J. A. Larsen, Lunar and Planetary Laboratory, reports his discovery of a comet on Spacewatch CCD images obtained with the 0.9-m f/3 reflector on Feb. 12.42 UT. Following posting on the NEO Confirmation Page, cometary appearance was also reported on CCD images taken around Feb. 13.3 by J. Young (Table Mountain, 0.6-m reflector; 6" coma of total mag 18.0 with little or no central condensation and a short, stubby tail 14" long in p.a. 260 deg) and by J. E. McGaha (Tucson, AZ, 0.36-m reflector; eighteen stacked images show a 6" coma and a 5" fan-shaped tail in p.a. 90 deg). [IAUC 8286, 2004 February 13]
An apparently asteroidal object discovered by the LINEAR project on February 3.40 has been found to show a narrow 1'.1 tail in p.a. 274 deg (slightly expanding toward the end) on CCD images obtained by R. H. McNaught with the 1.0-m f/8 reflector at Siding Spring on Mar. 30.8 UT. Following a request by the Central Bureau, M. Kocer reports that CCD frames taken at Klet on Mar. 31.145 also show a narrow tail about 90" long in p.a. approximately 280 deg. [IAUC 8314, 2004 March 31]
An apparently asteroidal object reported by the NEAT project on February 17.12, and posted on the NEO Confirmation Page, has been found to show apparent cometary appearance on CCD images taken by J. Ticha and M. Tichy (Klet, Feb. 20.8 UT; diffuse with a faint coma of diameter 10" and a possible tail in p.a. 225 deg) and by P. Birtwhistle (Great Shefford, Berkshire, U.K., Feb. 22.8 and 23.8; somewhat larger and less concentrated than stars of similar brightness, with a coma diameter of 9"-10", slightly extended in p.a. 270 deg). [IAUC 8294, 2004 February 27]
Brian Marsden notes on MPEC 2004-Q33 [2004 August 23] that
The "original" and "future" barycentric values of 1/a are +0.000259 and +0.000390 (+/- 0.000033) AU^-1, respectively.The "original" value suggests that this is not a "new" comet.
Subsequent observations with the 2.2-m reflector of the University of Hawaii showed it to have a coma, thus confirming its true cometary nature.
An apparently asteroidal object found by both the Spacewatch and LINEAR projects on CCD images taken on Feb. 17 has been found to have a 5" centrally condensed coma (of mag R = 18.7) and a 15" tail in p.a. 220-270 deg on CCD images taken on Mar. 16.3-16.6 UT by S. S. Sheppard, Y. R. Fernandez, and D. Jewitt with the University of Hawaii 2.2-m reflector. [IAUC 8305, 2004 March 15]
An apparently asteroidal object reported independently by the Catalina and LINEAR surveys (discovery observations on MPEC 2004-E02 and MPS 100749) has been found to have a 4"-diameter centrally condensed coma and a faint tail in p.a. 190-220 deg on R- band CCD images taken on Mar. 16 and 17 UT by S. S. Sheppard, Y. R. Fernandez, and D. Jewitt with the University of Hawaii 2.2-m reflector at Mauna Kea. [IAUC 8321, 2004 April 14]
An apparently asteroidal object reported independently by the Catalina and LINEAR surveys (discovery observations on MPS 102307; linked by G. V. Williams) has been found to be cometary on CCD images obtained at two Arizona observatories. Observations (via independent discovery) on Apr. 14.3 UT by M. T. Read and J. A. Larsen, using the 0.9-m f/3 Spacewatch reflector at Kitt Peak, show a tail 100" long in p.a. 300 deg, extending asymmetrically from the south part of the nuclear condensation. Exposures taken to look for cometary appearance on Apr. 14.32 by C. W. Hergenrother with the 1.2-m reflector at Mt. Hopkins show a very condensed 9" coma and a narrow tail 210" long in p.a. 295 deg. [IAUC 8322, 2004 April 15]
M. Hicks reports the discovery of a comet on CCD images taken with the 1.2-m Palomar Schmidt telescope in the course of the Near- Earth Asteroid Tracking project. The comet appeared soft and diffuse compared to nearby background stars, showing a coma of diameter 5" elongated east-west. Following posting on the NEO Confirmation Page, J. Young reported that CCD images taken by A. Grigsby and himself with the 0.6-m reflector at Table Mountain on Mar. 19.4 show a bright 4"-diameter coma with little central condensation and a weak fuzzy area about 12" long spanning p.a. 240-270 deg (but no distinct tail). [IAUC 8309, 2004 March 19]
The LINEAR project reports the discovery of a comet with a tail in p.a. approximately 235 deg on their images from Mar. 26.5 UT, with a previous observation the day before. Following posting on the NEO Confirmation Page, P. Holvorcem reports that three co-added unfiltered CCD images taken with the Tenagra 0.81-m telescope on Mar. 29.48 show the object to be diffuse with a 10" coma. [IAUC 8313, 2004 March 29]
Brian Marsden notes on MPEC 2004-L38 [2004 June 12] that
The "original" and "future" barycentric values of 1/a are +0.006430 and +0.006880 (+/- 0.000035) AU^-1, respectively.The "original" value suggests that this is not a "new" comet.
The NEAT program reports the discovery of a comet on images taken with the 1.2-m reflector at Haleakala, with a tail about 5" long toward the west. Following WWW posting on the NEO Confirmation Page, numerous observers have reported on the object's cometary appearance on CCD images taken during Mar. 28.9-29.4 UT, including F. Hormuth, J. Ticha and M. Tichy, P. Kusnirak, B. L. Stevens, J. Young, and G. Hug -- the object generally showing a coma diameter of 8"-30", total magnitude as bright as 16, and a faint tail approximately 20"-40" long spanning p.a. 240-285 deg.
The available astrometry, the following elliptical orbital elements, and an ephemeris appear on MPEC 2004-F82. The comet passed about 0.37 AU from Jupiter in July 2001, causing the perihelion distance to decrease. [IAUC 8313, 2004 March 29]
Kazuo Kinoshita calculates that this passage reduced the perihelion distance from 3.8 AU to 2.9 AU. The comet will approach Jupiter again in 2024, when the perihelion will be increased to 3.5 AU. The returns of 2005, 2013 and 2021 are the closest over the last 200 years. The comet should have been bright enough for discovery at earlier returns, which suggests that the change in perihelion distance has enhanced the activity of the comet.
On Mar. 28, A. C. Beresford, Myrtle Bank, South Australia, reported the visual discovery of a possible new comet close to the horizon in twilight by William A. Bradfield, during his search for sungrazing comets, from observations made with a 0.25-m reflector on Mar. 23.43 and 24.42 UT; further attempts to observe it had failed until the last few days. The delay in reporting was due to difficulties in matching the sketch of observations with star charts. [IAUC 8319, 2004 April 12]
Z. Sekanina, Jet Propulsion Laboratory, writes: "The comet's peculiar shape in the SOHO's C3 coronagraphic images is caused by two effects. The gradual coma broadening in a direction nearly perpendicular to the apparent motion, beginning before Apr. 18.8 UT, is caused by a rapid development of the comet's post-perihelion dust tail, which points to the southwest from the nucleus in the images taken around Apr. 19.5 and to the west in the more recent C3 images. The increasingly rugged boundary of the tail on its antisolar side, especially well pronounced after Apr. 18.8, is due to discrete features protruding through the tail's smooth leading edge. These protrusions are either streamers -- i.e., synchronic formations that are products of recurring events of briefly elevated dust emission (outbursts) -- or striae (i.e., pseudosynchronic formations of a more complex nature). If they are streamers (perhaps a more likely case, judging from their appearance in the images just before the comet's head left the C3 field-of-view), their sequence suggests fairly consistently an outburst recurrence period of about 0.5 day, which might indicate the comet's rotation period. For example, in the image of Apr. 19.496, one can identify at least seven features, whose position angles are estimated at between 150 deg and 240 deg, with the corresponding calculated event times between 2.4 days before perihelion and 0.6 day after perihelion. The peak radiation- pressure accelerations on the particles in the features are estimated at about 2-3 times the sun's gravitational acceleration."
K. Battams, Naval Research Laboratory, has reported measurements of the position of C/2004 F4 from the SOHO C3 images. [IAUC 8326, 2004 April 20]
The orbit, which puts perihelion at 0.17 AU on April 17.1, suggests that it should have been a relatively bright object during the winter and well placed in northern skies, so it is a little surprising that no-one picked it up. Perhaps it will be found in archival images. Alternatively the comet may have undergone an outburst, in which case its future behaviour becomes uncertain.
Brian Marsden notes on MPEC 2004-N32 [2004 July 12] that the "original" and "future" barycentric values of 1/a are +0.005164 and +0.004248 (+/- 0.000019) AU^-1, respectively. The original value suggests that this is not a "new" comet from the Oort cloud.
It entered the C3 coronagraph field on April 16 and left it on April 20; during the passage it brightened significantly, perhaps reaching -2 with a tail over 9 degrees long. Its elongation from the Sun rapidly increases and it will soon be visible in a dark sky. It remains a binocular object in the morning sky until June, passing through Pisces and Andromeda and is close to M31 in the second week of May. It will fade rapidly
I was able to recover the comet on April 23.14, estimating it at 2.6: in 20x80B in strong twilight. The comet was nearly stellar with hints of a tail. On April 26.1 it was an impressive sight in 20x80B with the tail stretching across the field of view. The coma was still highly condensed with a magnitude of 4.9. After a spell of cloudy weather I was able to observe it again on May 6.1, estimating it at 7.6 in 20x80B with a 0.3 degree tail. The coma was still highly condensed. It appears to be fading quite slowly, with reports in mid June suggesting that it is still 11th magnitude.
40 observations received so far suggest a preliminary light curve, corrected for aperture and where possible for systematic observer differences of m = 8.0 + 5 log d + 8.1 log r
Observations in ICQ format, last observation 2004 June 27, updated 2004 December 30.
H. Love, Lincoln Laboratory, MIT, reports the LINEAR discovery of a comet with a very diffuse coma and a diffuse tail roughly in p.a. 270 deg. [IAUC 8318, 2004 April 10]
An apparently asteroidal object reported by LINEAR, and posted on the NEO Confirmation Page, has been found to be diffuse by at least two different CCD observing groups, including M. Kocer at Klet (1.06-m KLENOT telescope on Apr. 16.8 UT) and A. Gilmore and P. Kilmartin at Mt. John (0.6-m reflector on Apr. 18.4). [IAUC 8325, 2004 April 18]
J. A. Larsen, Lunar and Planetary Laboratory, reports his discovery of a comet on Spacewatch images taken with the 0.9-m telescope at Kitt Peak; the object showed a coma diameter of 7" and a 15" tail in p.a. 240 deg. Following posting on the NEO Confirmation Page, other CCD observers also noted the object's cometary appearance, including J. G. Ries (McDonald Observatory, 0.76-m reflector; Apr. 21.24-21.43 UT; object extended with a hint of tail to the southwest), G. Hug (Scranton, KS, 0.3-m reflector; Apr. 21.4; diffuse), and J. Young (Table Mountain, 0.6-m reflector; Apr. 21.42-21.45; small central condensation in a round 4" coma, with a hint of elongation about 8" long in p.a. 290 deg). [IAUC 8328, 2004 April 21]
J. A. Larsen, Lunar and Planetary Laboratory, University of Arizona, reports the discovery of a comet on Spacewatch CCD images taken with the 0.9-m f/3 reflector at Kitt Peak, reporting a 17" tail in p.a. 280 deg. Following posting on the NEO Confirmation Page, J. E. McGaha (Tucson, AZ, 0.62-m f/5.1 reflector) reported that his stacked 3-min CCD frames taken on Apr. 24.22 UT show a soft coma with diameter 6" and a 8" tail in p.a. 270 deg. [IAUC 8332, 2004 April 24]
I was unable to see it in 25x100B on August 12, but Carlos Labordena reported it at 11.3 on August 14.89 in his 23.5cm SC.
On May 13, the Central Bureau was informed apparently independently by X.-m. Zhou, K. Cernis, and M. Mattiazzo of the existence of a possible unknown comet on the low-resolution ultraviolet SWAN images taken from the SOHO spacecraft. As there have been numerous never-confirmed reports to the Central Bureau of such objects over the last couple of years, despite a great exertion of effort to have them confirmed by ground-based observers, we proceeded with caution to try and get solid confirming evidence of a real comet. Reports trickled in (as can be seen from the table below), but successive attempts to produce search ephemerides met with some negative results that indicated some of the early positions were apparently not of the new comet. [IAUC 8346, 2004 May 27]
The orbit shows that it was at perihelion at 0.78 AU on May 12.7.
Brian Marsden notes on MPEC 2004-N33 [2004 July 12] that the "original" and "future" barycentric values of 1/a are -0.000124 and -0.000099 (+/- 0.000048) AU^-1, respectively. The original value suggests that this is a "new" comet from the Oort cloud.
37 observations received so far suggest a preliminary light curve, corrected for aperture and where possible for systematic observer differences of m = 7.2 + 5 log d + 13.5 log r
Observations in ICQ format, last observation 2004 August 21, updated 2004 December 30.
An apparently asteroidal object discovered by the LINEAR survey (discovery observation on MPS 105288) has been found to have cometary appearance by A. Gleason and J. Larsen on CCD exposures taken by J. Scotti with the Spacewatch telescope on Apr. 25.34-25.39 UT, when it showed a coma of diameter about 5" (and mag 17.6-17.9) and two tails: a diffuse component approximately 7" long in p.a. 350-355 deg and a very diffuse but more obvious tail approximately 10"-16" long spanning p.a. 275-335 deg. [IAUC 8333, 2004 April 30]
Subsequent observations revealed a faint tail and hints that the object was not stellar. The latest orbit is parabolic, with perihelion at 3.1 AU towards the end of December 2003.
An apparently asteroidal object discovered by the Spacewatch survey (discovery observation from MPS 106357 and MPEC 2004-H91) has been reported by D. J. Tholen, University of Hawaii (UH), to be cometary on two 400-s R exposures taken on May 8.3 UT by F. Bernardi, J. Pittichova, and N. Moskovitz with the UH 2.24-m telescope on Mauna Kea. There is a faint tail approximately 55" long in p.a. about 24 deg and a hint of a second, fainter tail almost 15" long in p.a. 310 deg. The measured PSF widths of the comet head are 1".03 and 0".95 in the two images, while the widths of 55 trailed astrometric reference stars in the images range from 0".90 to 1".09, not sufficient to resolve the presence of a coma. R. H. McNaught reports that images obtained on Apr. 30.6 at Siding Spring also suggest a slightly soft image for the comet. [IAUC 8337, 2004 May 9]
An apparently asteroidal object reported by the Catalina Sky Survey, and posted on the NEO Confirmation Page, has been found by T. Spahr to show a weak coma with a possible very faint extension to the west on CCD images obtained by J. B. Battat and himself (Mt. Hopkins 1.2-m reflector) on May 24.4 UT; the FWHM of the comet image is 20 percent larger than other stars of similar brightness in the field. R. Stoss reports that CCD images taken by S. Sanchez, J. Nomen, and himself on May 24.1 (0.30-m reflector, Mallorca) shows the object to have a softer image than surrounding field stars. [IAUC 8343, 2004 May 24]
Brian Marsden notes on MPEC 2005-G29 [2005 April 5] that
The "original" and "future" barycentric values of 1/a are +0.000854 and +0.000585 (+/- 0.000001) AU^-1, respectively.The original value suggests that this is probably not a "new" comet from the Oort cloud.
A comet has been discovered by R. H. McNaught on CCD images obtained with the 0.5-m Uppsala Schmidt telescope at Siding Spring. Following posting on the NEO Confirmation Page, J. Young reported that CCD images obtained with the 0.6-m reflector at Table Mountain on May 25.5 UT show an 8"-10" coma with no apparent central condensation and a straight, narrow tail 20"-30" long in p.a. 252 deg. CCD images taken by A. C. Gilmore and P. M. Kilmartin with the 0.6-m reflector at Mount John on May 25.7 show a circular 5" coma and no tail. [IAUC 8348, 2004 May 28]
An apparently asteroidal object reported by LINEAR, and posted on the NEO Confirmation Page, has been found to have cometary appearance on CCD images taken by P. Birtwhistle (Great Shefford, U.K.; coma diameter 12" with a hint of a 9"-wide extension emanating from a 3" central condensation for approximately 20" in p.a. 90 deg) and by P. Holvorcem and M. Schwartz (Tenagra Observatories, Nogales, AZ; 0.81-m f/7 reflector; 5" coma). [IAUC 8350, 2004 June 11]
An apparently asteroidal object discovered by the LINEAR project, and posted on the 'NEO Confirmation Page', has been found to show cometary appearance (5" round coma without condensation) by J. Young (0.6-m reflector, Table Mountain) on CCD images taken on June 14.3-14.4 UT. [IAUC 8352, 2004 June 14]
Brian Marsden notes on MPEC 2005-G30 [2005 April 6] that
The "original" and "future" barycentric values of 1/a are +0.001393 and +0.001366 (+/- 0.000002) AU^-1, respectively.The original value suggests that this is probably not a "new" comet from the Oort cloud.
An apparently asteroidal object reported by LINEAR, and posted on the 'NEO Confirmation Page', has been found to show cometary appearance on CCD images taken by G. Masi (Las Campanas, 0.35-m reflector, June 17.2 UT; round coma with diameter 6"-8") and by J. E. McGaha (Tucson, AZ, 0.62-m reflector, June 17.3; 5-min exposure shows a 10" coma and a 15" fan-shaped tail in p.a. 300 deg). [IAUC 8356, 2004 June 17]
Brian Marsden notes on MPEC 2005-K03 [2005 May 16] that
The "original" and "future" barycentric values of 1/a are +0.001330 and +0.001060 (+/- 0.000012) AU^-1, respectively.The original value suggests that this is probably not a "new" comet from the Oort cloud.
Maik Meyer provides the following information on the linkage with the NEAT images:
Comet precovery by Maik Meyer [from http://www.hohmanntransfer.com/mn/0409/20.htm]
It came right after my little son went to bed and I was preparing for a comet observing session, so I had time without family duties. I quickly checked for earlier images of this comet and SkyMorph indicated two days in 1996 in NEAT data with an asteroidal brightness of 18 mag. I was not very hopeful but almost fell off my seat when I saw the bright 16-mag. comet with a coma and a tiny tail on my screen.
I quickly measured the two days, composed the message to the MPC, and, when I came back from my comet observing, MPEC 2004-S18 had been issued containing the observations and updated orbits for the 1996 and 2004 apparitions. I still wonder why this one slipped through NEAT's detection, because it is so obvious. Now this comet will become numbered ? my second precovery which leads to a permanent numbering after 159P/LONEOS.
An apparently asteroidal object, designated 2004 NL_21 on the basis of LINEAR observations on July 15 and 16 (MPS 110794) and for which the Minor Planet Center has published several "cometary" orbits (cf. e.g., MPEC 2004-O40, MPO 66393, MPEC 2004-S06), has been reported to be of cometary appearance by R. H. McNaught from observations with the 0.5-m Uppsala Schmidt telescope at Siding Spring. Sixty-second CCD exposures on Sept. 6.6 UT showed a near-asteroidal condensation with a narrow fan tail extending about 40" in p.a. 220 deg; on Sept. 18.5 there was a tail about 60" long in p.a. 230 deg. [IAUC 8408, 2004 September 23]
Following the identification by M. Meyer (cf. MPEC 2004-S18) of 1996 observations of comet P/2004 NL_21 (cf. IAUC 8408), on exposures taken via NEAT at Haleakala, the comet has received the permanent number 160P (cf. MPC 52734, 52764, 52766). [IAUC 8414, 2004 October 3]
Observations in ICQ format, last observation 2004 October 13, updated 2004 October 19.
While the retrograde nature of the orbit of 2004 NN8 is certain, the size of the orbit is very poorly constrained. At one extreme, the orbit could be parabolic (or even hyperbolic). At the other, orbits with semimajor axes smaller than 4 AU are not excluded by the currently available observations. The solution above is based on the assumption that 2004 NN8 is similar to objects such as 1999 LE31 and (20461) Dioretsa. Further observations are very much desired, as are observations with large-aperture instruments to clarify the physical nature of this object. The difference in plane-of-sky between the above solution and a parabolic solution on Aug. 17 amounts to -0m.23 in R.A. and -1'.1 in Decl.Further observations, most recently in late March 2005, suggest that it was at perihelion at 2.35 AU in late October 2004. The semimajor axis is 96 AU, the eccentricity 0.98 and the inclination 165 degrees. Aphelion is at 190 AU, with the period just under 1000 years.
K. J. Lawrence, Jet Propulsion Laboratory, reports the discovery by the NEAT project on August 5.32 of a slightly diffuse comet (coma diameter about 3") on CCD images taken with the Palomar 1.2-m Schmidt telescope. Following posting on the 'NEO Confirmation Page', other CCD observers have remarked on the object's cometary appearance, including J. Ticha and M. Tichy at Klet (1.06-m telescope; object diffuse with an asymmetric coma or faint tail toward p.a. 250 deg and red mag 18.7-18.8 on Aug. 7.92 UT; coma diameter 13" and faint tail in p.a. 250 deg on Aug. 8.88); P. Birtwhistle at Great Shefford, Berkshire, England (0.30-m f/6.3 reflector; object distinctly diffuse with a diameter of 10" -- three times the size of star images of similar brightness on co- added images taken on Aug. 7.94-7.96); and P. Kusnirak at Ondrejov (0.65-m f/3.6 reflector; diffuse with coma diameter 10" on Aug. 7.93 and 7.97). [IAUC 8383, 2004 August 8]
Brian Marsden notes on MPEC 2004-U11 [2004 October 18] that The "original" and "future" barycentric values of 1/a are +0.000024 and -0.000096 (+/- 0.000075) AU^-1, respectively. The original value suggests that this is probably a "new" comet from the Oort cloud.
Observations in early June 2005 revealed a faint coma to the object, which had been classified as a Centaur type asteroid, with a period of 65 years and perihelion at 11.8 AU.
Roy Tucker provides the following discovery information:
With my system at Goodricke-Pigott Observatory, I do an all-night scan-mode image of a strip of sky 48 arcminutes wide centered at declination +02 degrees, 5 minutes with three 35-centimeter aperture f/5 Newtonian telescopes with 1K-squared CCDs at the foci. The telescopes are spread in the east-west direction so that they image the same sky but separated in time by about twenty minutes. Their aiming is centered about 40 minutes to the east of the meridian. During data acquisition, the scan is chopped into 1024x1024-pixel FITS images, each covering about 0.64 square degrees. Imaging begins in the evening twilight and continues until morning twilight.
Summer is not prime observing time in Tucson, Arizona. We have a seasonal monsoon from early July until mid-September like clockwork. I haven't seen Perseid meteors here in years. My first bit of luck was that I got four consecutive clear nights from the 20th through the 23rd of August.
The object announced yesterday in MPEC 2004-Q43 as comet C/2004 Q1 (Tucker) was actually recorded on the morning of the 22nd, but in an image triplet just a few fields from the end. After looking at blinking images for a couple of hours, I sometimes get a little eager to finish up. I actually did report a faint asteroid in another part of the field, but I was so fixated on looking for faint moving objects that I missed the big moose wallowing across the field.
Fortunately, the 23rd was clear and the comet was well positioned near the middle of the field of view (in the cropped frame seen above). When I got to that image triplet, I immediately noticed it, but didn't think too much about it. I see known comets pass through my field fairly often and, indeed, had seen comet 53P/Van Biesbroeck pass through on the 20th and the 21st. I went to the Minor Planet Center's Web site and used the MPChecker function to find out what the object was. When it reported no known objects in that area, I became very interested.
I immediately composed an astrometry report for those observations and E-mailed them to the Minor Planet Center with the heading "comet" and inquired if this was a known object. After a bit of time, Kyle Smalley responded that this appeared to be an unknown object and requested a physical description. During the wait for this response, I realized that I should have recorded it the previous night. A short search revealed the previous images and I sent those astrometric measures to the MPC. So, although the formal discovery image was recorded on the 23rd of August, I was actually able to provide observations for the previous night within a short time. The object was then posted on the NEO Confirmation Page and other observers quickly verified it.
So, I was lucky three ways. 1) I had good weather at just the right time, 2) nobody else saw it between my observations of the 22nd and the 23rd, and 3) the other surveys were working mostly to the west. Of course, it helps to look at large numbers of images. Each clear night provides me 500 to 700 images to examine, depending upon season. I'll get perhaps 190 clear, dark nights per year, which means a little over 100,000 images per year.
Although the discovery was very exciting, the operation that produced it is very routine. MOTESS is a "discovery machine"; photons go in and discoveries come out. I don't actually do much except look at a lot of images. I go to bed pretty early and rise early to shut down the instrument and begin processing the data. It's a pleasant change from the usual astronomical observing in that I can get a good night's sleep and go to a day job refreshed.
Roy Tucker's day job is CCD engineer at the University of Arizona. MOTESS is short for "Moving Object and Transient Event Search System," a project that received a 2002 Planetary Society Eugene Shoemaker Grant (update). His other discoveries include NEA 2003 UY12 and PHA 2004 MP7.
Roy A. Tucker, Tucson, AZ, reports his discovery of a comet with a coma diameter of about 50" and a 70" tail in p.a. about 230 deg on unfiltered CCD images taken with a 0.35-m reflector. Following posting on the 'NEO Confirmation Page', the object was also noted to be cometary on CCD images taken by J. Foster (University Hills, Los Angeles, CA, 0.32-m f/5.6 reflector; fan tail in p.a. 235 deg on Aug. 24.4 UT) and by J. E. McGaha (Tucson, AZ, 0.36-m f/10 reflector; faint 26" coma with a very faint fan-shaped tail 30" long in p.a. 250 deg on Aug. 25.35). Images by Tucker on Aug. 25.5 show a 30" coma and a tail about 40" long in p.a. 255 deg. [IAUC 8393, 2004 August 25]
Brian Marsden notes on MPEC 2004-U30 [2004 October 23] that The "original" and "future" barycentric values of 1/a are +0.005264 and +0.005985 (+/- 0.000010) AU^-1, respectively. The original value suggests that this is not a "new" comet from the Oort cloud.
108 observations received so far suggest a preliminary light curve, not corrected for aperture but where possible for systematic observer differences of m = 1.5 + 5 log d + 27.5 log r
Observations in ICQ format, last observation 2005 May 4, updated 2005 May 11.
Don Machholz provides the following discovery information:
I began comet hunting on Jan 1, 1975, and for nearly 30 years now I've done some comet hunting each and every month. At the time I found this comet I had searched 7046 hours, 1457 since my previous find, in 1994, when I found three comets in four months (go figure!)There were some early suggestions that the orbit was periodic and linked with comet 1532 R1, which has a suggested linkage with a progenitor of 2002 C1 (Ikeya-Zhang). The prediscovery observations however rule out this possibility.
When I found this latest one I was on my back deck, using my 6" (15cm) Criterion Dynascope (purchased in 1968). I used a 2" OD eyepiece pressed over the focussing tube, yielding 30x and a field of view of about 2 degrees. This is the same setup I use for my Messier Marathons, and I used it last March to find all 110 objects by memory in one night. I'm very comfortable with it. I use it on my back deck from time to time to compliment the 10" reflector and 5" homemade binoculars I have in my observatory 30 meters from my house. With the 6" in the deck I can see down to -45 degrees declination. I had covered some of the southern sky on Aug 25, then went back out on Aug 27 to cover more sky, working my way eastward after each N-S sweep.
Donald Edward Machholz reports his visual discovery of a comet (his tenth) with a 0.15-m f/8 reflector, at 30x, on Aug. 27.467 UT.
2004 UT R.A. (2000) Decl. Mag. Observer Aug. 27.511 4 16.8 -22 20 11.2 Machholz Aug. 27.660 4 16 28.5 -22 22 50 Garradd D. E. Machholz (Colfax, CA). Coma diameter 2' moderate degree of condensation (position and physical measurements made with a 0.25-m reflector at 64x). Motion < 1 deg/day eastward. G. Garradd (Siding Spring). 0.5-m Uppsala Schmidt telescope + CCD. Coma diameter 1', with a 3' tail in p.a. about 320 deg. Position rough (center of comet uncertain within overexposed coma).[IAUC 8394, 2004 August 27]
J. J. Gonzalez, Leon, Spain, reports that a visual observation made from Alto del Castro with a 0.20-m reflector on Aug. 28.16 UT yielded total mag 10.9 and coma diameter 2'.3. P. Birtwhistle, Great Shefford, Berkshire, England, reports that CCD images obtained with a 0.30-m f/6.3 Schmidt-Cassegrain reflector on Aug. 28.15 show a coma of diameter 70" and a broad tail 5' long in p.a. 240 deg. R. Behrend, Geneva Observatory, reports that CCD images by C. Vuissoz and himself with the 1.20-m Euler reflector on Aug. 28.4 show a coma diameter of 1' and a 3' tail in p.a. 240 deg. [IAUC 8395, 2004 August 28]
D. H. Wooden, NASA Ames Research Center; D. E. Harker, University of California, San Diego; C. E. Woodward and M. S. Kelley, University of Minnesota; S. J. Bus and A. Tokunaga, University of Hawaii; C. Magri, University of Maine; R. P. Binzel, Massachusetts Institute of Technology; and G. Lo Curto and E. Wenderoth, European Southern Observatory (ESO), report that K-, N-, and Q-band photometry of comet C/2004 Q2 was obtained on Oct. 18.64 UT using the NASA Infrared Telescope Facility (+ SpeX guider camera). The coma was extended (FWHM = 5", FWZI = 12"); aperture photometry in a 3"-diameter aperture yields K [2.2 microns] = 8.49 +/- 0.1. The comet was also observed on Oct. 23.31 with the ESO 3.6-m telescope (+ TIMMI2) at La Silla, yielding the folowing flux densities in a 3"-diameter aperture: N_1 (8.6 microns), 0.53 +/- 0.04 Jy; Q_1 (17.75 microns), 1.50 +/- 0.14 Jy. The comet was also extended in the N_1 band (FWHM = 3", FWZI = 5"). Spitzer InfraRed Spectrograph observations of the comet are planned for Nov. 13. [IAUC 8431, 2004 November 7]
J. H. Sastri and R. Vasundhara, Indian Institute of Astrophysics, Bangalore, reports that R-band CCD images of comet C/2004 Q2 were obtained in January by K. Kuppuswamy and C. Velu with the 1.02-m f/13 telescope at the Vainu Bappu Observatory, Kavalur, which reveal dust fans via the spatial filter of Larson and Sekanina (1984, A.J. 89, 571) with the following lengths (+/- 15") and position angles (+/- 10 degrees) for each of the three fans: Jan. 2.6625 UT, fan 1, 150" in p.a. 291 deg; fan 2, 150" in p.a. 252 deg; fan 3, 60" in p.a. 216 deg. Jan. 15.6344, fan 1, 150" in p.a. 282 deg; fan 2, 150" in p.a. 239 deg; fan 3, 30" in p.a. 211 deg. The dust features were modeled after Vasundhara (2002, A.Ap. 382, 342), indicating that the latitude ranges of the active regions on the nucleus that produce the fans are as follows (direction of fitted north rotational pole R.A. = 190 deg +/- 10 deg, Decl. = +50 deg +/- 10 deg, equinox 2000.0): fan 1, -15 to 0 deg; fan 2, -50 to -35 deg; fan 3, -78 to -70 deg. Assuming silicate grains of size 0.1-30 microns and Fulle's (1987, A.Ap. 171, 327) relation between grain velocity and the forces on each grain, a rotation period of 0.38 +/- 0.08 day is estimated for the comet's nucleus. Naked-eye total-magnitude estimates by J. Gonzalez, Asturias, Spain: Jan. 9.81 UT, 3.4; 17.07, 3.7; 22.80, 4.1; 31.95, 4.3; Feb. 7.81, 4.8. [IAUC 8480, 2005 February 9]
Brian Marsden notes on MPEC 2004-U31 [2004 October 23] that The "original" and "future" barycentric values of 1/a are +0.000404 and +0.001856 (+/- 0.000015) AU^-1, respectively. The original value suggests that this is probably not a "new" comet from the Oort cloud.
Observations in mid September put the comet at around 10th magnitude and it had brightened to 8th magnitude by mid October. I was able to observe it in 20x80B from outside Cambridge on November 14.1, estimating it at 7.3. David Seargent reports that it is just visible to the naked eye from really dark sites at 6.2. By mid December it was widely visible to the naked eye, and had brightened to around 4.5. In early January it became very well placed for observation and reached its brightest at around 3.5. By mid February it had faded to 5th magnitude, but was still a naked eye object. It is now slowly fading, but remains well placed for northern hemisphere observers.
Images from the Campocatino Austral Observatory, including a fantastic movie of the ion tail.
1087 observations received so far suggest a preliminary light curve of m = 5.2 + 5 log d + 9.3 log r
Observations in ICQ format, last observation 2005 May 30, updated 2005 June 1.
R. H. McNaught reports his discovery of a comet on CCD images taken by himself with the 0.5-m Uppsala Schmidt telescope at Siding Spring on Sept. 2.4 UT, when the object was diffuse with a hint of a tail to the southeast. Images taken by McNaught with the Siding Spring 1.0-m f/8 reflector on Sept. 4.4 show the comet to be diffuse with a 10" coma and a tail 15" long in p.a. 110 deg. [IAUC 8398, 2004 September 4]
J. Young (Table Mountain, 0.6-m reflector + CCD) reports that images taken in poor seeing (and at low altitude) on Sept. 6.13- 6.16 UT show a coma diameter of about 5". Additional CCD images by R. H. McNaught with the Siding-Spring 1.0-m reflector on Sept. 6.5 show an ill-defined center of brightness that is elongated in the direction of tail (and of the comet's motion). [IAUC 8400, 2004 September 6]
Stuart Rae estimated the comet at 9.7 on September 10, a little brighter than the ephemeris estimate. By September 15 it had brightened to 8.4 and had become more condensed. Images from the Campocatino Austral Observatory
G. Pojmanski, Warsaw University Astronomical Observatory, reports the discovery by the 'All Sky Automated Survey' (ASAS) of a comet on CCD V images taken on Sept. 3.40 UT with the ASAS-3V instrument (a 200-mm-f.l., 70-mm-aperture, f/2.8 telephoto lens; pixel size 14".8) at Las Campanas (measurements of ASAS-3V images given below). A. Hale (Cloudcroft, NM, 0.20-m reflector) reports total visual mag 10.9 and coma diameter 2'.5 (diffuse without condensation) on Sept. 9.47. [IAUC 8402, 2004 September 9]
18 observations received so far suggest a preliminary light curve, corrected for aperture and where possible for systematic observer differences of m = 10.1 + 5 log d + 8.2 log r, which suggests it might reach 3rd magnitude in early October, however it is showing signs of fading, suggesting it may not survive perihelion.
Observations in ICQ format, last observation 2004 September 27, updated 2005 January 5.
On Sept. 15 the NEAT project at Jet Propulsion Laboratory reported to the Minor Planet Center observations from Sept. 13 of a cometary object observed at Palomar in collaboration with M. Brown, California Institute of Technology. Observations with the 1.2-m Schmidt telescope showed the object to be diffuse with a coma about 5" across and condensation of 2" but no evident tail. The Minor Planet Center then established that the object was identical with an unremarkable, presumed main-belt minor planet for which it had linked observations from Sept. 10 and 13 reported by LINEAR. The two "discovery" observations are as follows:
2004 UT R.A. (2000) Decl. Mag. Observer Sept.10.29965 0 37 23.60 +14 18 11.9 20.1 LINEAR 13.26186 0 35 27.70 +14 21 11.6 19.1 NEATFollowing placement on "The NEO Confirmation Page" further observations were received, among them a report from G. Jones, Tucson, AZ (0.32-m Ritchey-Chretien reflector), to the effect that on Sept. 16.20 UT the object had a coma of diameter 3" and a 10" tail in p.a. 230 deg, as well as one from J. Young, Table Mountain Observatory (0.6-m reflector), remarking that on Sept. 16.23 there was a 5" coma (with no apparent central condensation) and a fan- shaped tail between p.a. 210 deg and 270 deg extending about 8"; a straight, narrow spike extended 40" in p.a. 236 deg. [IAUC 8407, 2004 September 23]
M. Bezpalko, Lincoln Laboratory, reports the LINEAR discovery of an apparent comet with a short tail in p.a. about 195 deg on Nov. 20.435 UT. This object was identified by the Minor Planet Center with the apparently asteroidal object 2004 RG_113 (also found by LINEAR; cf. MPS 113143 -- Sept. 19 batch). [IAUC 8444, 2004 November 23]
Brian Marsden notes on MPEC 2004-Y10 [2004 December 18] that
The "original" and "future" barycentric values of 1/a are +0.001764 and +0.002993 (+/- 0.000017) AU^-1, respectively.showing that the comet is not a "new" one.
M. E. Van Ness, Lowell Observatory, reports his discovery of a comet on CCD images taken by himself with the 0.59-m Schmidt LONEOS telescope (discovery observation below), reporting an 8" moderately condensed coma with a fan-shaped tail 155" long in p.a. 225 deg. B. A. Skiff reports that LONEOS images taken by himself on Sept. 27.4 UT show a nearly circular, poorly condensed coma of red mag 18.0 and about 12" across in bright moonlight. Following posting on "The NEO Confirmation Page", J. E. McGaha (Tucson, AZ, 0.36-m f/10.0 Schmidt-Cassegrain reflector + CCD) reports that 20 stacked 60-s exposures from Sept. 27.3 show an unusual appearance, with a split fan-shaped tail 18" long in p.a. 280 deg and 250 deg, and an elongated coma in p.a. 260 deg and no sharp central condensation; McGaha's 30 stacked exposures on Sept. 28.3 also show a diffuse, elongated coma 14" (axis along p.a. 265 deg-85 deg) x 4", again with no sharp condensation, and an 8" fan-shaped tail in p.a. 225 deg. J. Young reports that CCD frames taken with the Table Mountain 0.6-m reflector on Sept. 28.28-28.38 show a 4" coma without any central condensation and a very wide fan-shaped tail about 6"-8" long spanning p.a. 205 deg-280 deg, and a narrow 25" 'spike' in p.a. 255 deg. [IAUC 8412, 2004 September 28]
Observations in ICQ format, last observation 2004 October 13, updated 2004 October 19.
K. J. Lawrence, Jet Propulsion Laboratory, reports the NEAT discovery of a comet on images taken with the Haleakala telescope, the object described as having a coma of diameter about 25", with elongated images but no obvious tail. The comet was also observed earlier on the same night (with prediscovery observations on Sept. 21) by the LINEAR team, which made no comment on the object's appearance; both "discovery" observations are tabulated below. Following posting on "The NEO Confirmation Page", numerous observers have reported on the object's cometary appearance on CCD images obtained during Oct. 5.9-6.6 UT, including M. Tichy (Klet), P. Birtwhistle (Great Shefford, U.K.), C. Jacques and E. Pimentel (Belo Horizonte, Brazil), D. T. Durig and G. A. T. Morris (Sewanee, TN), J. E. McGaha (Tucson, AZ), G. R. Jones (Tucson, AZ), and D. Higgins (Canberra, Australia). The general consensus is that there is a diffuse coma of diameter about 16"-30" and a faint, broad, fan- shaped tail about 1' wide and 4'-5' long in p.a. approximately 240-280 deg. P. Kusnirak (Ondrejov) reports the fan tail in p.a. about 290 deg and another tail about 4' long in p.a. about 240 deg. [IAUC 8416, 2004 October 6]
Observations in ICQ format, last observation 2004 November 16, updated 2004 December 30.
An object discovered at Siding Spring on 0.5-m Uppsala Schmidt telescope CCD images by R. H. McNaught on October 12.69 has been found (after posting on the 'NEO Confirmation Page') to be diffuse on CCD images taken at Las Campanas with the 0.36-m 'SoTIE' reflector by G. Masi, F. Mallia, and R. Wilcox on Oct. 13, 17, and 21. Ten combined 1-min exposures taken on Oct. 13.1 UT show a slightly diffuse object with diameter about 15" (slightly elongated northwest-southeast) with an apparent condensation in the northwest part of the coma; images taken on Oct. 17.3 show a possible 5" tail in p.a. 10 deg. [IAUC 8421, 2004 October 21]
An apparently asteroidal object discovered on Oct. 10 by the Siding Spring Survey (announced as 2004 TU_12 on MPEC 2004-T55; discovery observation below) has been found to show a short eastward tail. CCD images taken over 2.5 hr with the 0.36-m "SoTIE" reflector at Las Campanas by F. Mallia, G. Masi, and R. Wilcox on Nov. 12.0 UT show a tail about 2' long in p.a. 70 deg (the "head" appearing like stars in the field (FWHM about 3"). Eighty 30-s CCD images taken on Nov. 12.8 by J. Lacruz (La Canada, Spain) show a sharp tail 4' long in p.a. 69 deg (and total mag 14.3). [IAUC 8436, 2004 November 12]
G. Masi, Ceccano, Italy, reports further on their CCD images of this comet (cf. IAUC 8436), noting that the tail was brighter close to the comet's head on Nov. 12.0 UT; on Nov. 14.2 and 15.1 the tail was faint (barely visible) close to the nuclear condensation while peaking in intensity about 100" and about 130", respectively, from the comet's head. On Nov. 14.2 and 15.1, the total tail length was > 5'.8 and > 10', respectively, always pointing toward p.a. 70 deg. Images taken on Nov. 17.04-17.07 show the tail to be definitely fainter than on the previous night, being barely visible for the first 1' from the comet's head but clearly brighter beyond that point (visible to > 6', beyond the edge of the frames); the first 3'.3 of the tail was in p.a. 72 deg, with a sudden change at that point to p.a. 73 deg. [IAUC 8439, 2004 November 17]
Two additional comets have now been numbered: 161P/Hartley-IRAS (P/1983 V1 = P/2004 V2; IAUC 8428) and 162P/Siding Spring (P/2004 TU_12; IAUC 8436). [IAUC 8445, 2004 November 24]
The 14th magnitude object was discovered by Rob McNaught during the Siding Spring Survey on October 10.55. It will fade. It has been linked to objects seen in 1990 (by the Palomar Sky Survey), 2000 (by LINEAR and LONEOS) and by ESO, AMOS and NEAT in following years, so the orbit is secure and it was numbered 162. It has a period of 5.32 years, with perihelion at 1.23 AU and was at perihelion on November 10.
An apparently asteroidal object discovered by LINEAR on October 19.42 has been found to show a faint coma on CCD images taken on Oct. 20.1 UT by A. Knoefel (Schoenbrunn, Germany; 0.5-m f/5 reflector). CCD images taken by P. Birtwhistle (Great Shefford, U.K.; 0.30-m f/6.3 reflector) on Oct. 21.2 show the object to be possibly diffuse with diameter 9" and a possible broad tail 12" long in p.a. 320 deg. [IAUC 8421, 2004 October 21]
In October 2005 a faint secondary component was reported.
Brian Marsden notes on MPEC 2004-Y11 [2004 December 18] that
The "original" and "future" barycentric values of 1/a are +0.000712 and +0.001041 (+/- 0.000038) AU^-1, respectively.showing that the comet is probably not a "new" one.
Observations in ICQ format, last observation 2005 January 8, updated 2005 February 8.
B. Skiff, Lowell Observatory, reports his discovery of a comet on LONEOS images obtained on Nov. 4.1 UT with the 0.59-m Schmidt telescope, the object showing a moderately condensed coma of diameter 25" and a weak tail 50" long in p.a. 75 deg. Following posting on the "NEO Confirmation Page", B. L. Stevens (Las Cruces, NM, 0.3-m Schmidt-Cassegrain telescope) reports that his CCD images taken on Nov. 4.2 show a 30" tail in p.a. 55 deg. [IAUC 8426, 2004 November 4]
R. H. McNaught, Siding Spring Observatory, reports his recovery of comet P/1983 V1 (= 1983v = 1984 III) on CCD images taken with the 1.0-m f/8 reflector on Nov. 3.7 and 5.8 UT. The comet appears slightly diffuse with no tail. The indicated correction to the predictions on MPC 45657 (ephemeris on MPC 52656) and in the 2004 Comet Handbook is Delta(T) approximately -4.8 days. [IAUC 8428, 2004 November 5]
Two additional comets have now been numbered: 161P/Hartley-IRAS (P/1983 V1 = P/2004 V2; IAUC 8428) and 162P/Siding Spring (P/2004 TU_12; IAUC 8436). [IAUC 8445, 2004 November 24]
John Davies and Simon Green of Leicester University reported the discovery of a fast moving object by IRAS (the Infra-Red Astronomy Satellite) on 1983 November 11. On being asked to confirm the object, Ken Russell of the UK Schmidt Telescope Unit reported that Malcolm Hartley had discovered a comet on a plate taken 6 days earlier, that was probably the same object, but due to moonlight it wasn't captured on a confirming plate until November 23. The comet has a retrograde orbit (just) with a period of 21.5 years, and 2005 is its first return since discovery. It reached 10th magnitude in 1984 January and should attain a similar magnitude this time round. It emerges sufficiently far from the Sun for observation from the UK in 2005 June, by which time it is nearing its brightest. Moving north from Andromeda, it rapidly becomes circumpolar, passing some 9 degrees from the pole in July. It slowly fades and we should be able to follow it until September, by which time it has crossed into Canes Venatici. On its way out from perihelion at its next return it will pass fairly close to Jupiter in 2028, an encounter that will reduce the perihelion distance from its current 1.28 AU to 1.22 AU.
R. H. McNaught, Siding Spring Observatory, reports the discovery of an object on November 3.40 on images taken by G. J. Garradd with the 0.5-m Uppsala Schmidt telescope in the course of the Siding Spring Survey; McNaught later (Nov. 5 and 6) found the object to be slightly diffuse on CCD images taken with the Siding Spring 1.0-m f/8 reflector. [IAUC 8429, 2004 November 6]
K. J. Lawrence, Jet Propulsion Laboratory, reports the NEAT discovery of a comet on November 5.45 on images taken with the 1.2-m Schmidt telescope at Palomar, the object showing very slight coma, but no tail. R. H. McNaught confirms that the object shows a slightly diffuse nuclear condensation and a 40"-long fan tail centered in p.a. 280 deg (the fan spanning 25 deg) on 240-s images obtained with the Siding Spring 1-m reflector on Nov. 6.7. [IAUC 8429, 2004 November 6]
Maik Meyer has found images of the comet on Palomar DSS plates from 1990 and 1991, and NEAT images from 1997. This gives a secure orbit and lead to the comet being numbered 163.
Following the identification of observations of comet P/2004 V4 (cf. IAUC 8429, 8438) in 1990-1991 and 1997 (cf. MPC 53257, 53303, 53307), the comet has been numbered 163P. [IAUC 8468, 2005 January 18]
The Catalina Sky Survey has reported observations of two short-tailed comet suspects on four CCD frames obtained over a 39-min span on Nov. 10.5 UT (observer R. Hill; 0.68-m Schmidt telescope). The head of the slightly fainter of the two was situated about 102" west and 33" north of that of the brighter and close to end of the latter's tail. Assuming that the two orbits differed only in T, B. G. Marsden, Harvard-Smithsonian Center for Astrophysics, found that the objects -- if real -- had to be intermediate-period comets some 4.3-4.4 AU from the earth. The assumption also revealed likely LINEAR observations of a single asteroidal object on Oct. 8 and 24, and a three-night linkage then showed identity with the LINEAR asteroidal object 2003 YM_159, observed on 2003 Dec. 17 and 30 (see MPS 109905) -- the identity clearly being with the brighter 2004 Nov. 10 object, now designated component A. T for component B will occur about 0.23 day later than for component A. [IAUC 8433, 2004 November 10]
The comet was originally named LINEAR-Catalina, however Brian Marsden notes on MPEC 2004-V79
Consultation with the IAU Committee on Small-Body Nomenclature has yielded the decision to introduce for this comet (cf. IAUC 8433, MPEC 2004-V52) the new principal designation P/2004 V5 and to replace the name LINEAR- Catalina with LINEAR-Hill. The components A and B are defined as before, The orbital elements and ephemeris refer to component A. Component B will pass perihelion 0.23 day after component A.
While the initial report inferred that the discovery of comet P/2003 YM_159 at Catalina was a team discovery (thus the name 'LINEAR-Catalina' given on IAUC 8433), it has since been determined that observer Rik Hill was alone in discovering, measuring, and reporting the comet -- thereby allowing his name to be used in place of the survey name (as also approved by the Catalina team). Consultation with the IAU Committee on Small-Body Nomenclature has yielded the decision to introduce for this comet the new principal designation P/2004 V5 and to replace the name 'LINEAR-Catalina' with 'LINEAR-Hill'. The components A and B are defined as before. The improved orbital elements on MPEC 2004-V79 are for component A, with the preliminary elements for component B being well satisfied with the same elements but with Delta(T) = +0.23 day. [IAUC 8438, 2004 November 15]
Z. Sekanina, Jet Propulsion Laboratory, writes that his comet fragmentation model (cf. IAUC 8434) shows that the two nuclei of P/2004 V5 (MPECs 2004-V79 and 2004-W07) broke apart around 2001.9 +/- 0.3 year, at a heliocentric distance of about 6.3 AU and 2.5 years before perihelion. The separation velocity of the companion (fragment B) relative to the primary (A) pointed below the orbital plane and was at least 2.6 m/s. The motion of B has since been subjected to a differential deceleration of 40 +/- 6 units of 10**-5 the solar attraction. Predicted separations and position angles of B relative to A are as follows (equinox 2000.0): 2004 Nov. 21.0 TT, 131", 287 deg; Dec. 1.0, 137", 288 deg; 11.0, 144", 289 deg; 21.0, 152", 290 deg; 31.0, 159", 290 deg; 2005 Jan. 10.0, 167", 291 deg; 20.0, 175", 291 deg; 30.0, 181", 291 deg. [IAUC 8440, 2004 November 18]
Rik Hill is a BAA Member and has provided this discovery frame.
On Nov. 30, M. Mattiazzo (Adelaide, S. Australia) reported that he noticed images of a faint object moving on SWAN images (his positions have uncertainties of a degree or more due to the poor resolution of the ultraviolet imager on SWAN/SOHO), speculating then that, if real, the object might become visible in the days ahead in the C3 coronagraph. Today, S. Hoenig has reported the appearance of a comet with a tail in C3 images, which K. Battams reports has brightened slightly from mag about 6.5 on Dec. 16.26 UT to about 6.1 on Dec. 16.70-16.74. A span of 14 hours of SOHO astrometry by Battams appears on MPEC 2004-Y02 (reduced by B. G. Marsden). It does appear that the SWAN object is identical with the SOHO object. [IAUC 8455, 2004 December 16]
Observations in ICQ format, last observation 2005 January 11, updated 2005 January 18.
An apparently asteroidal object discovered by LONEOS, designated 2004 VR_8 (cf. MPS 118755, MPEC 2004-V48; discovery observation below), has been found to show a 10"-diameter coma and a tail 16" long in p.a. 140 deg on R-band CCD observations taken by C. W. Hergenrother (Lunar and Planetary Laboratory) with the 1.54-m Kuiper reflector at Catalina on Nov. 19.3 UT. Also, A. Nakamura (Kuma, Ehime, Japan) reports that 240-s unfiltered CCD frames taken with a 0.60-m reflector on Dec. 8.55 and 9.55 shows to object's image to be slightly 'softer' than other field stars of similar brightness, and a possible very faint tail is visible to the southeast. [IAUC 8451, 2004 December 10]
An apparently asteroidal object discovered by LINEAR on November 22.32, and published as 2004 WR_9 on MPO 120656, has been found to show cometary appearance. P. Birtwhistle, Great Shefford, U.K., reports that CCD images taken on Dec. 7.0 UT with a 0.30-m f/6.3 reflector show the object as having a tail 20" long in p.a. 235 deg and a very concentrated coma with a diameter of 9", while on images from Dec. 3.0, there had been a suggestion of a 10" tail in p.a. 250 deg. C. Hergenrother reports that R-band images taken with the Catalina 1.54-m reflector on Dec. 8.45 show a highly condensed coma 11" in diameter and a faint tail > 25" long in p.a. 235 deg. [IAUC 8448, 2004 December 8]
A. Milner, Lincoln Laboratory, reports the discovery by LINEAR of a comet with an apparent tail in p.a. 90 deg (discovery observation below). Following posting on the 'NEO Confirmation Page', other observers have confirmed the object's cometary nature from CCD images, including E. J. Christensen at Catalina (0.68-m Schmidt telescope, Dec. 9.10-9.11 UT; coma diameter about 8" with red mag 16.2-16.6 and faint 20" tail in p.a. 60 deg) and M. Tichy, M. Kocer, and J. Ticha at Klet (1.06-m KLENOT telescope, Dec. 9.70; diffuse with coma diameter 25" and a wide tail in p.a. 70 deg). It is possible that this comet is of short period. [IAUC 8449, 2004 December 9]
An apparently asteroidal object discovered by the LINEAR project (discovery observation below), and posted on the 'NEO Confirmation Page', has been found to be cometary in appearance. R-band observations taken by C. Hergenrother with the Catalina 1.54-m reflector on Dec. 9.55 UT show a coma 25" in diameter and a slightly curved 50" tail in p.a. 325 deg. CCD images taken by J. E. McGaha (Tucson, AZ, 0.36-m f/10 reflector) on Dec. 10.4 show a 3" coma with a 12" tail in p.a. 300 deg. [IAUC 8450, 2004 December 10]
An apparently asteroidal object discovered by the LINEAR project on December 15.46, and posted on the 'NEO Confirmation Page', has been found to show a round 4" coma in CCD images taken in poor seeing on Dec. 20.5 and 21.5 UT by J. Young with the 0.6-m reflector at Table Mountain, who adds that five stacked images taken on the latter date show the head to be slightly elongated. Images taken by M. Tichy at Klet on Dec. 21.1 (1.06-m reflector) show a diffuse 8" coma. [IAUC 8457, 2004 December 21]
Brian Marsden notes on MPEC 2005-D12 [2005 February 21] that
The "original" and "future" barycentric values of 1/a are +0.000006 and -0.000647 (+/- 0.000042) AU^-1, respectively.showing that the comet is a "new" one from the Oort cloud.
Eric J. Christensen, Lunar and Planetary Laboratory, reports his discovery of a comet in the course of the Catalina Sky Survey on images taken with the 0.68-m Schmidt telescope on December 21.47, noting a coma of diameter about 15" and a fan-shaped tail 20" long in p.a. 270 deg. Following posting on the 'NEO Confirmation Page', J. Young writes that his images taken at Table Mountain on Dec. 22.4 UT show the object with a round 8" coma and a broad fan-shaped tail spanning p.a. 210-290 deg (the faint tail edge at p.a. 210 deg extends 20", while the brighter edge at p.a. 290 deg extends only 14"). [IAUC 8458, 2004 December 22]
Following the identification of observations in 1998 Jan. and Apr. (cf. MPC 53463), comet P/2004 Y1 (cf. IAUC 8458) has been numbered 164P/Christensen. [IAUC 8474, 2005 February 1]
Observations with the Dupont 2.5-m reflector at Las Campanas at the end of November and beginning of December 2005 finally showed cometary characteristics and the object has been confirmed as a comet.