Updated 2010 March 19
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 in ICQ format.
Full text of IAU Circular announcements will not be given until the circular is publicly available.
This comet has apparently undergone a rapid brightening (ephemeris on IAUC 7600). M. Mattiazzo, Wallaroo, South Australia, notes that the total visual magnitude has brightened by about 2.5 mag in the 24 hr ending Mar. 30.5 UT, with the comet becoming noticeably more condensed in the same period. Visual m_1 estimates and coma diameters: Mar. 26.82, 10.8, 2'.5 (R. J. Bouma, Groningen, The Netherlands, 0.25-m reflector); 28.44, 10.7, 3'.5 (Mattiazzo, 0.20-m reflector); 28.98, 10.9, 3' (P. M. Raymundo, Salvador, Brazil, 0.25-m reflector); 29.27, 10.9, 2'.0 (M. Linnolt, Honolulu, HI, 0.25-m reflector); 29.46, 10.8, 3'.0 (Mattiazzo); 29.94, 9.5, 3'.5 (A. Amorim, Florianopolis, Brazil, 0.14-m reflector); 30.45, 8.6, 2'.9 (Y. Nagai, Yamanashi, Japan, 0.32-m reflector); 30.40, 8.2, 5' (S. T. Rae, Whakatane, New Zealand, 10x50 binoculars); 30.52, 8.0, 3'.0 (Mattiazzo, McLaren Vale, S. Australia, 25x100 binoculars); 30.81, 7:, 5' (K. Cernis, Vilnius, Lithuania, no instrument given). [IAUC 7605, 2001 March 30]
C. W. Hergenrother, M. Chamberlain, and Y. Chamberlain, Lunar
and Planetary Laboratory, University of Arizona, report that 60-s
R-band images of C/2001 A2 taken on Apr. 30.12 UT with the Catalina
1.54-m reflector show a double nucleus. The two components are
nearly equal in brightness and 3".5 apart and aligned precisely on
an east-west line. Both components are highly condensed.
Observations (with the same telescope) on Apr. 24.14 show only a
Visual m_1 estimates: Apr. 20.93 UT, 7.2 (J. G. de S. Aguiar, Campinas, Brazil, 11x80 binoculars); 21.46, 7.4 (M. Mattiazzo, Wallaroo, S. Australia, 7x50 binoculars); 23.16, 6.7 (C. S. Morris, Fillmore, CA, 20x80 binoculars); 25.35, 6.4 (S. T. Rae, Whakatane, New Zealand, 8x21 binoculars); 27.48, 6.4 (A. Pearce, Nedlands, W. Australia, 8x40 binoculars); 29.95, 6.3 (W. Souza, Sao Paulo, Brazil, 11x80 binoculars); 30.49, 6.3 (Pearce). [IAUC 7616, 2001 May 1]
J. Broughton, Reedy Creek, Queensland, writes that his CCD observations (0.25-m f/6.6 Schmidt-Cassegrain) on May 9.3 UT showed the brighter (western) component at m2 = 14.7, with the secondary, 0.3 mag fainter, perhaps 5" distant in p.a. 100 deg, although some elongation of the secondary could make the separation as much as 7". On May 10.3 the appearance was similar. On May 11.3 the western component had brightened to m2 = 13.2, and the eastern component had virtually disappeared. On May 12.4 the western component had faded to m2 about 14.0, while the secondary was then perhaps 2 mag fainter, 8".5 away in p.a. 100 deg.
Using the absolute astrometry for Apr. 30 (see IAUC 7616) and May 9 given on MPC 42656 (where the western primary is labeled B and the eastern secondary is labeled A), Z. Sekanina, Jet Propulsion Laboratory, obtained a separation time of Mar. 17 +/- 12 and an acceleration of 7.1 +/- 2.4 (in units of 10**-5 solar gravity).
Total visual magnitude estimates by A. Pearce, Nedlands, Western Australia (20 x 80 binoculars): May 9.48 UT, 6.2; 11.44, 5.3; 13.49, 5.2; 14.49, 5.4; 15.49, 5.4. [IAUC 7625, 2001 May 15]
E. Jehin, A. Jaunsen, H. Boehnhardt, M. Kiekebusch, H. Nunez, R. Amestica, C. Herrera, J. Navarete, F. Delgado and R. M. West, European Southern Observatory, report: "Images of comet C/2001 A2 have been obtained using the 8.2-m Very Large Telescopes Melipal and Yepun with the Nasmyth and Cassegrain test cameras, respectively. On May 14.98 UT two components were seen in R-band images, the eastern, tailward one (component A) about 1 mag fainter than component B (within an aperture of 1".3) at a separation of 12".6 in p.a. 105 deg. Both components had individual comae elongated approximately in the antisolar direction. Component B showed sunward-extended isophotes in the very inner part of the coma. On May 16.98 UT the distance between the components had increased to 14".6 (in the same position angle). In addition, the sunward fragment appeared to have split into two components with a separation of 1" in p.a. 135-315 deg; these components were of about the same brightness (in R) and surrounded by a joint coma. V-band images revealed very extended isophotes perpendicular to the separation direction of this new pair. This could indicate the presence of a large amount of gas in the coma in addition to the dust."
J. Broughton, Reedy Creek, Queensland (0.25-m Schmidt-Cassegrain), reports further CCD astrometry on May 14.4 and 16.3 UT, noting that on the latter occasion component A was at least two magnitudes fainter than and was separated from component B by about 14" in p.a. 102 deg. [IAUC 7627, 2001 May 17]
Z. Sekanina, Jet Propulsion Laboratory, writes: "Astrometric offsets of component A from B reported between Apr. 30 and May 18 (IAUC 7616, 7625, 7627, MPC 42656, MPEC 2001-K14) indicate that the splitting occurred on Mar. 29.9 +/- 1.6 UT (thus coinciding with the major outburst) and that the companion's relative deceleration is 15.2 +/- 0.7 units of 10**-5 solar attraction. Predicted separations and position angles: May 21, 19", 110 deg; 26, 28", 115 deg; 31, 39", 121 deg; June 5, 54", 128 deg; 10, 74", 136 deg; 15, 97", 145 deg; 20, 122", 156 deg. Assuming that the separation of component C (IAUC 7627) from B coincided with the outburst of May 11, the single available offset suggests that C is subjected to a deceleration of approximately 40 units of 10**-5 solar attraction. Preliminary predicted ephemeris: May 21, 3", 138 deg; 26, 8", 142 deg; 31, 16", 148 deg; June 5, 29", 154 deg."
Total visual magnitude estimates: May 16.96 UT, 5.3 (V. A. Buso, Rosario, Argentina, 0.06-m reflector); 17.90, 5.3 (W. Souza, Sao Paulo, Brazil, 11 x 80 binoculars); 19.89, 5.2 (Souza, 8 x 30 binoculars); 21.44, 5.4 (A. Pearce, Nedlands, Western Australia, 20 x 80 binoculars); 22.46, 5.2 (Pearce). D. A. J. Seargent, Cowra, New South Wales (25 x 100 binoculars), writes that on May 14.4 UT there was a narrow ion tail, intense for about 1 degree, traced for approximately 4 deg in p.a. 133 deg; on May 15.4 a diffuse "cloud" was visible, detached from the tail, at about 1.5 deg from the coma. [IAUC 7630, 2001 May 22]
D. Schleicher, Lowell Observatory; and R. Greer, Wittenberg University, write: "We obtained six sets of narrowband photometry of comet C/2001 A2 on June 27 and 28, using the Hall 1.1-m telescope at Lowell Observatory, with the following averaged results: log Q(OH) = 28.68; log Q(CN) = 26.09; log Af(rho) = 2.46 (445 nm; cf. IAUC 7342). The equivalent log Q(water; vectorial) is 28.81. No significant temporal or aperture variations were observed." [IAUC 7653, 2001 June 29]
O. Schuetz, E. Jehin, X. Bonfils, H. Boehnhardt, K. Brooks, A. Delsanti, O. Hainaut, E. Jourdeuil, P. Leisy, M. Sterzik, and E. Wenderoth, European Southern Observatory (ESO); J. Helbert, DLR, Berlin; G. Garradd, Loomberah, N.S.W.; F. Marchis, University of California at Berkeley; B. Stecklum, TLS-Tautenburg; and G. Tozzi, Osservatorio Astrofisico di Arcetri, report that an intensive high-resolution monitoring of the inner coma on June 16-21 indicates that the comet continues to fragment. The images obtained at ESO (La Silla) in the thermal infrared with the 3.6-m telescope (+ TIMMI2, N band), and in the optical region with the 3.5-m New Technology Telescope (+ EMMI, R filter) and the ESO/MPG 2.2-m telescope (+ WFI, R filter), show faint companions drifting away from the principal nucleus (B) in an approximately antisolar direction. Analysis by Z. Sekanina, Jet Propulsion Laboratory, shows that all the observations can be satisfied by three fragments, D, E, and F. The observed offsets (separation from B and position angle), the fragment identification, and the instruments used are as follows: June 16.422 UT, 2".8, 212 deg, D+E+F (TIMMI2); 17.447, 4".6, 215 deg, E+F (TIMMI2); 18.409, 6".7, 222 deg, F (WFI); 18.449, 6".5, 219 deg, F (TIMMI2); 18.456, 6".6, 222 deg, F (EMMI); 19.433, 4".7, 222 deg, D (WFI); 19.433, 7".2, 222 deg, E and/or F (WFI); 19.449, 5".0, 223 deg, D (EMMI); 19.449, 8".5, 223 deg, E and/or F (EMMI); 20.433, 6".1, 231 deg, D (WFI); 20.433, 8".3, 222 deg, E (WFI); 21.437, 11".0, 223 deg, E (TIMMI2); 21.442, 7".2, 231 deg, D (EMMI); and 21.442, 10".6, 222 deg, E (EMMI). The analysis implies that fragment D separated from B on June 3.5 +/- 1.8 with a differential nongravitational deceleration of 17 units (of 10**-5 the solar attraction) and with an initial velocity of 1.0 +/- 0.1 m/s (approximately normal to the orbit plane); fragment E on June 9.5 +/- 0.7 with a deceleration of 53 units and a velocity of 0.3 +/- 0.1 m/s; and fragment F on June 11.3 +/- 0.5 with a deceleration of 102 units and a velocity of 0.8 +/- 0.2 m/s. These breakup events apparently triggered another major outburst (cf. IAUC 7630), reported by visual observers to have peaked on June 12.
Total-visual-magnitude and coma-diameter estimates: July 1.05 UT, 4.4, 20' (R. Haver, Frasso Sabino, Italy, 10x50 binoculars); 1.71, 4.5, 16' (S. Yoshida, Ibaraki, Japan, 10x24 binoculars); 2.69, 4.7, 10' (M. Mattiazzo, Wallaroo, S. Australia, 7x50 binoculars; moonlight); 3.08, 5.0, 18' (A. Giambersio, Potenza, Italy, 16x70 binoculars); 3.95, 4.5, 12' (D. V. Fedotov, Kharkov, Ukraine, 7x50 binoculars); 4.75, 4.8, 20' (Y. Nagai, Yamanashi, Japan, 12x50 binoculars; moonlight). [IAUC 7656, 2001 July 5]
L. M. Woodney and D. G. Schleicher, Lowell Observatory; and R. Greer, Wittenberg University, report narrowband gas and dust imaging of this comet: "On June 29-30, the comet displayed CN jet(s) symmetrical about p.a. 250 deg. Three successive arcs separated by approximately 12 000 km were observed on each side; outward motion of the arcs was detected. These arcs were not observed in the dust continuum." [IAUC 7666, 2001 July 18]
M. Kidger, Instituto de Astrofisica de Canarias, reports: "Monitoring of the inner coma by the Spanish Comet Observers Team reveals two small photometric events that are possibly related to the ejection of small fragments from the nucleus. Representative CCD R magnitudes, using a 10" aperture and the USNO A2.0 catalogue for reference stars: July 23.996 UT, 12.62 (R. Ferrando, Pla D'Arguines, 0.26-m Schmidt-Cassegrain); 24.889, 12.80 (P. Manteca, Begues, 0.26-m Schmidt-Cassegrain); 25.936, 12.4 (D. Rodriguez, Madrid, 0.20-m Schmidt-Cassegrain); 29.853, 12.79 (Manteca); 30.933, 12.92 (Manteca); 31.881, 12.85 (Manteca); Aug. 2.896, 12.95 (Manteca); 3.844, 13.1 (Manteca); 7.84, 13.4 (R. Ligustri, Latisana, Italy, 0.2-m reflector); 7.852, 13.4 (Ferrando). The lightcurve indicates events of amplitude 0.4 and 0.2 mag initiating at approximately July 25.0 and 30.0 respectively. For comparison, the major event around July 12 (cf. IAUC 7659, 7676) had an amplitude of 1.5 mag (10" aperture). This indicates that, if due to fragmentation, these later events were probably caused by the separation of small, short-lived splinters that may not have been directly observable." [IAUC 7679, 2001 August 9]
P. D. Feldman, H. A. Weaver, and E. B. Burgh, Johns Hopkins University, report observations of comet C/2001 A2 with the Far Ultraviolet Spectroscopic Explorer beginning July 12.58 UT and coinciding with the photometric event reported on IAUC 7679: "Spectra (range 91-118 nm; spectral resolution 0.03 nm) were obtained using the 30" x 30" aperture. Several new cometary emissions were identified, particularly the (0,0) bands of the CO Birge-Hopfield systems (C-X and B-X) at 108.8 and 115.1 nm, respectively; O I [(^1)D-(^1)D] at 115.2 nm; and three lines of the H_2 Lyman system at 107.16, 111.86, and 116.68 nm, pumped by solar Lyman-beta fluorescence. Also detected were O I multiplets at 98.9, 102.7, and 104.0 nm, and several lines of the H I Lyman series. The rotational envelopes of the CO bands are resolved and appear to consist of both cold and warm components, the cold component accounting for 80 percent of the flux and having a rotational temperature of 60 K. The warm component may be indicative of a CO_2 source. Both the CO bands and the O I 115.2-nm emission (an indicator of H_2O production) decreased by a factor of two over the 7.5 hr observation. Preliminary estimates of the production rates at the beginning of the observation are Q(CO) = 4 x 10^(27) s^(-1) and Q(H_2O) = 3 x 10^(29) s^(-1) (vectorial model). These values may be uncertain by as much as a factor of two, due to uncertainties in the solar flux. No emission is detected from Ar I at 104.8 and 106.7 nm and He I at 58.4 nm (in second order). We derive Q(Ar) = 6 x 10^(25) s^(-1) (5-sigma upper limit), which implies that Ar/O is more than a factor of ten less than solar. In addition to the features listed above, more than two dozen other emissions remain unidentified." [IAUC 7681, 2001 August 15]
A. Lecacheux, Observatoire de Paris, on behalf of the Odin Team (http://www.snsb.se/Odin/Odin.html), reports: "The H_2O 110-101 line at 556.936 GHz was observed in C/2001 A2 with high spectral resolution (54 m/s) with the ODIN submillimeter space telescope from June 20 until July 12. From a preliminary analysis, 10' x 10' mapping made during July 1.5-2.4 UT shows that the H_2O coma is elongated along the comet-sun line; the integrated line intensity inside the 2' beam peaks at 12 K km s**-1, on the main- beam brightness temperature scale. The line width indicates an H_2O outflow velocity of 0.7 km/s. The estimated water-production rate for July 1.7-2.0 is 3.8 x 10**28 molecules/s." [IAUC 7706, 2001 September 6]
David Seargent reported a visual observation at 13.1 on March 14, a little brighter than expected. It brightened very rapidly and reached 8th mag by the end of the month. It continued to brighten and became more condensed as it approached the sun. An estimate by Andrew Pearce on April 20.51 put it at 7.1 in 20x80B. Several estimates on April 24 commented that the comet had brightened rapidly in the last 24 hours and was now around 6.5. By the end of April it had reached 6th mag, but during early May the rate of brightening has slowed significantly, perhaps associated with the nuclear splitting observed at the end of April. More rapid brightening resumed around May 10 and the comet reached around 5th mag. An obsevation from Michael Mattiazzo on May 17.42 put it at 5.2 in 7x50B with a tail at least 1.6 degrees long; the comet was also visible to the naked eye. As of May 21 it was still 5th mag. Andrew Pearce reported that the comet had brightened to 4.8 on May 31.44 and the comet had a 1.5 degree long tail. The coma was noticeably blue-green in colour. On June 11.91 Andrew reported further brightening, estimating the comet at 3.6 to the naked eye and a 1.7 degree long tail in 20x80B. Michael Mattiazzo photographed the comet on June 12.
Giovanni Sostero recovered the comet on June 27. I picked it up on July 1.05 with 7x50B and estimated it at 5.3. It was an easy object, well condensed and diameter 11'. On July 10.9 it was an easy object in 8x30B of about mag 5.5, DC3 and diameter 12'. A further outburst took place on July 12, and on July 12.95 it was just visible to the naked eye from central Cambridge.
Michael Mattiazzo points out that the orbital plane crossing took place around July 15-16th. From this, we may expect enhancement of a dust tail in the solar and anti solar directions.
The comet is now fading quite rapidly and has become very diffuse, making it a difficult object to pick out against the Milky Way background. Observations in mid August put it at around 9th magnitude, DC 1 - 2 and around 6' diameter. Observing on August 28.06 with my 0.20-m SCT x75 I made it 10.8, DC1 and diameter 2.3'
879 observations give a preliminary uncorrected light curve of 7.3 + 5 log d + 10.6 log r, with several small outbursts after the major one at the end of March, another a week or so later and a third in mid June as can be seen in the light curve. This also suggests that there was quasi- periodic variation in the light curve with an amplitude of about a magnitude.
Observations in ICQ format, last observation 2001 November 16, updated 2002 August 8.
Observations in ICQ format, last observation 2002 March 4, updated 2002 April 2.
S Nakano was able to link the comet with an asteroid 2000 HR81, first observed by LONEOS on 2000 April 29.28. The new orbit, which is similar to the preliminary one, shows that the comet is a first time visitor to the inner solar system with 1/a (orig) of 0.000049. [MPEC 2001-H23, 2001 April 21]
Further to IAUC 7582, D. Hammer reports his measurements for a comet found by M. Oates on SOHO website images. C/2001 C5 was visible in both the C3 and C2 coronagraphs, and D. Biesecker provides the following post-perihelion V magnitudes from the C2 data (the C3 data being poor due to vignetting): Feb. 13.854, 5.4; 13.896, 5.0; 13.938, 5.0; 13.979, 4.9; 14.021, 4.9; 14.064, 4.9; 14.104, 5.3; 14.146, 5.6; 14.163, 6.3; 14.188, 7.4. The reduced observations and retrograde parabolic orbital elements (T = 2001 Feb. 13.3 TT, q = 0.026 AU, i = 166.3 deg; a direct orbit solution is also possible) by B. G. Marsden appear on MPEC 2001-D07. [IAUC 7585, 2001 February 20]
Comet 2001 UT R.A. (2000) Decl. C/2001 C5 Feb. 13.721 21 41.2 -13 25
Observations in ICQ format, last observation 2001 February 15, updated 2002 April 2.
The IAU Committee on Small Bodies Nomenclature has agreed upon the names for the following five comets: C/2000 S3 (LONEOS); 150P/2000 WT_168 (LONEOS); C/2000 Y2 (Skiff); C/2001 G1 (LONEOS); C/2001 HT_50 (LINEAR-NEAT). [IAUC 7674, 2001 July 30]
Brain Marsden notes on MPEC 2002-G37 [2002 April 10] that the "original" and "future" barycentric values of 1/a are +0.000027 and -0.000117 (+/- 0.000009) AU**-1, respectively. This indicates that it is a new comet from the Oort cloud.
The IAU Committee on Small Bodies Nomenclature has agreed upon the names for the following five comets: C/2000 S3 (LONEOS); 150P/2000 WT_168 (LONEOS); C/2000 Y2 (Skiff); C/2001 G1 (LONEOS); C/2001 HT_50 (LINEAR-NEAT). [IAUC 7674, 2001 July 30]
Brain Marsden notes on MPEC 2003-A28 [2003 January 6] that the "original" and "future" barycentric values of 1/a are +0.000878 and +0.001234 (+/- 0.000001) AU**-1, respectively. This indicates that it is not a new comet from the Oort cloud.
The comet emerged from solar conjunction in the late summer. Observations in September and October show a small diffuse coma, with the comet around 11th magnitude. By December the comet was clearly fading and was around 13th magnitude in the Northumberland refractor.
109 observations give a preliminary light curve of 7.3 + 5 log d +  log r
Observations in ICQ format, last observation 2004 October 12, updated 2004 October 19.
MPEC 2001-J34 contains 40 astrometric observations May 11-15 and parabolic orbital elements (T = 2001 Mar. 19, q = 1.00 AU, Peri. = 279 deg, Node = 198 deg, Incl. = 11 deg, equinox 2000.0) computed from 26 of them. The orbit is still very indeterminate, and it is not clear whether or not the comet is of short period. [IAUC 7625, 2001 May 15] The comet is intrinsically very faint.
As hinted on IAUC 7625, this is a short-period comet, and observations by C. W. Hergenrother, T. B. Spahr, and M. Nelson with the 1.8-m f/1 VATT Lennon telescope on May 27 make it clear that the orbital period is $P$ about 7.5-7.9 years. Spahr has also identified the comet with a very faint object (not described as cometary) discovered by A. E. Gleason with the Spacewatch telescope on 2000 Oct. 7 and placed on The NEO Confirmation Page but removed on Oct. 20 for lack of follow-up. The additional astrometry and orbital elements ($P$ = 7.64 yr) are given on MPEC 2001-K43. S. Nakano has noted some rough similarity to the orbit of comet 3D/Biela. [IAUC 7635, 2001 May 29]
Brian Marsden has provided some additional information about this possibility: While I cannot exclude with 100-percent certainty the possibility that the new comet P/2001 J1 (NEAT) is the long-lost 3D/Biela, I really don't think it is.
What, indeed, happened to 3D/Biela after 1852? Did it break up completely? Some 30 years ago I looked into the possibility of finding that comet again and published a number of different orbits based on different possibilities for the action of the nongravitational forces on the comet after 1852. For an epoch around 1971 these orbits all had perihelion distances under 0.83 AU and inclinations to the ecliptic under 8.1 degrees.
Coming now to the recent comet, although unusually large inconsistencies among the observations made it particularly difficult to establish the orbit, and given that the comet's position in the sky makes it difficult to observe, I note that some careful observations on May 27 by Carl Hergenrother and Tim Spahr with the Vatican Advanced Technology Telescope in Arizona isolated the revolution period to 7.5-7.9 years. Tim then realized that the object had in fact been reported as unusual--though not of cometary appearance--by Arianna Gleason at Spacewatch on October 7 last year. The object was then listed on The NEO Confirmation Page for almost two weeks, although it was obviously too faint for essentially all of the likely follow-up observers, and Spacewatch itself evidently just missed the comet's position when it recorded the region again on October 19. The October 7 linkage is clearly correct, and this pins down the current period as 7.64 years.
Running this orbit back gives a moderately close approach to Jupiter (0.8 AU) in 1972, before which the P/2001 J1 perihelion distance was 0.96 AU and the inclination 11 degrees. While there was tolerably good agreement in orbital eccentricity, argument of perihelion and nodal longitude, it is difficult to reconcile the perihelion distance and inclination with the 3D/Biela values. To get these elements to agree would require the nongravitational forces to act in some special way, together with the gravitational effects of occasional approaches to Jupiter.
Whether or not the comets are identical, why was the current comet not observed earlier in the twentieth century? After all, the perihelion distance of under 1 AU does allow moderately close approaches to the earth--with a minimum orbital distance of perhaps 0.15 AU and an actual minimum distance of perhaps 0.5 AU in 1955. Actually, it is quite clear that at many passages through perihelion the small elongation from the sun would completely preclude observations, and by the time the object had moved around to opposition it would be as faint as when Spacewatch fortuitously observed it last October. Even under the more favorable circumstances of the 1955 perihelion passage, the best one could hope for at a 90-degree elongation from the sun would be magnitude 15, and more typically (as this year), one would have to contend with a maximum elongation of 70-80 degrees and magnitude 16 if one were lucky. We _were_ lucky that NEAT was observing this year so far from opposition, and there would have been no observing program with the capability of making the discovery at the previous comparable elongation in 1985. Unless the comet is now anomalously faint, that it escaped prior detection is fully reasonable--a situation not a bit like that of 3D/Biela on several occasions in the late eighteenth and early nineteenth centuries.
Observations in ICQ format, last observation 2001 July 12, updated 2001 July 13.
11 observations give a preliminary light curve of 5.4 + 5 log d +  log r
Observations in ICQ format, last observation 2003 July 27, updated 2004 September 19.
M. D. Hicks, Jet Propulsion Laboratory, reports that this comet shows a diffuse coma of diameter about 5" and a faint tail about 7" long in p.a. 240 deg in a 10-min R-band CCD exposure obtained on June 30.3 UT with the 0.61-m reflector at Table Mountain (observers D. Esqueda, Hicks, and T. Ha). Hicks' name also should be added to the list of NEAT team members on IAUC 7654. [IAUC 7655, 2001 July 2]
Further selected total-visual-magnitude and coma-diameter estimates: Nov. 14.27 UT, 7.2, 12' (C. S. Morris, Fillmore, CA, 10x50 binoculars; 1.1-degree tail); 19.95, 6.3, 18' (R. Haver, Frasso Sabino, Italy, 10x50 binoculars); 22.91, 5.8, 20' (B. H. Granslo, Fjellhamar, Norway, 7x50 binoculars); 30.78, 5.7, 15' (J. J. Gonzalez, Asturias, Spain, 7x50 binoculars); Dec. 3.38, 5.4, 21' (Y. Nagai, Yamanashi, Japan, 7x35 binoculars); 3.79, 5.3, - (Gonzalez). [IAUC 7766, 2001 December 5]
39 visual observations give a preliminary uncorrected light curve of 11.3 + 5 log d +  log r
Observations in ICQ format, last observation 2002 March 12, updated 2002 April 14.
Further to IAUC 7655, D. Hammer reports measurements of three additional comets found by M. Oates, X. Leprette, and S. Hoenig on SOHO website images. All three objects were visible with the C2 coronagraph, and C/2001 O1 was also visible in C3 images. The reduced astrometry and orbital elements by B. G. Marsden appear on the MPEC cited below; C/2001 N1 does not seem to be a Kreutz sungrazer, whereas the other two comets do. [IAUC 7667, 2001 July 19]
Comet 2001 UT R.A. (2000) Decl. MPEC C/2001 M11 June 27.254 6 18.6 +22 03 2001-N24 C/2001 N1 July 5.896 6 55.7 +21 07 2001-N24 C/2001 O1 16.221 7 29.8 +19 15 2001-O03
Observations in ICQ format, last observation 2002 August 8, updated 2003 February 2.
Regarding the announcement of this comet on IAUC 7673, the observations on July 25 were made at Haleakala, while those on July 29 were made at Palomar. Additional astrometry and very uncertain parabolic orbital elements (from 17 observations, July 25-Aug. 1) and an ephemeris appear on MPEC 2001-P01. [IAUC 7676, 2001 August 1]. The comet is a distant one, past perihelion and will fade.
As the clue of a cometary type orbit suggested, this object did eventually show cometary activity and is brightening rapidly. I observed it on February 9.81 and estimated it at 11.3: in the Thorrowgood refractor. On March 28.84 I was able to see it in the same instrument, despite strong moonlight and observing through trees, estimating it at 10.2. The comet is now fading and is quite a diffuse object making it difficult to locate.
An apparently asteroidal object reported by LONEOS was announced on MPEC 2001-P40 last Aug. 13. Numerous observers could not detect any cometary activity, despite the cometlike orbit. Now approaching perihelion, the object has finally shown cometary activity, detected by several observers as indicated by the following reported total magnitudes and coma/tail data from CCD images: Jan. 11.44 UT, 16.1, 0'.4 coma, 0'.5 tail in p.a. 230 deg (A. Nakamura, Kuma, Ehime, Japan, 0.60-m reflector); 22.39, 14.7, diffuse (S. Wakuda, Shizuoka, Japan, 0.25-m reflector); Feb. 1.40, 13.5, 0'.9 coma, broad tail toward west with the longest segment being 0'.9 long in p.a. 220 deg (Nakamura); 1.41, 12.8, fan-shaped coma spanning p.a. 200-345 deg (T. Oribe, Saji, Tottori, Japan, 1.03-m reflector). Recent astrometry and the orbital elements appear on MPEC 2002-C04. [IAUC 7814, 2002 February 2]
From Astronomy.com, 24 August 2001
Large Earth-Crossing Asteroid Found A newly discovered rare asteroid may be the largest Earth-crosser known.
by Vanessa Thomas
During the past decade, astronomers have begun finding members of an unusual breed of asteroids. Called Damocloids after the first of their kind discovered, 5335 Damocles, these asteroids have elliptical orbits that resemble those of short-period comets like Comet Halley. A new member of this strange astronomical club has now been found, and its brightness suggests that it might be the largest Earth-crossing asteroid known.
Provisionally titled 2001 OG108, the object was first spotted on July 28 by Michael Van Ness, an observer for the Lowell Observatory Near-Earth-Object Search (LONEOS) program in Arizona. Over the next two weeks, observers tracked the newfound asteroid to determine its path about the sun. Like other Damocloids, 2001 OG108 has an elongated orbit. Each trip about the sun takes it from beyond Uranus to just within Earth's orbital path.
Because Damocloids mimic the course of short-period comets, astronomers suspect these unique asteroids might actually be "dead" comets. While the gas and ices that cause comets to flare up when they approach the sun may have been exhausted, the dark, rocky remains continue to travel through the solar system. If this notion is correct, these asteroids should have the same dark surfaces typical of short-period comet nuclei.
However, 2001 OG108 is one of the brightest Earth-crossing asteroids found so far. According to LONEOS director Ted Bowell, just two other Earth-crossers rival it in brightness. But 1866 Sisyphus and 2000 WF129 orbit the sun in the inner solar system and are unlikely to be as intrinsically dark as 2001 OG108, Bowell says. If the newly discovered asteroid is darker and reflects less light than Sisyphus and 2000 WF129, but appears just as bright, it must be larger.
Based on its brightness, its current distance, and an expectation of its albedo, Bowell estimates that 2001 OG108 could be as large as 10 miles (15 kilometers). The median size of the approximately 800 known Earth-crossing asteroids is less than one kilometer, so "this object really sticks out," he says.
Although 2001 OG108 will occasionally zip past Earth during its 50-year journey about the sun, Bowell assures that Earthlings need not worry that the asteroid will impact Earth - at least not in the near future. In its present orbit, the Damocloid will not come any closer to us than about 28 million miles (about 45 million kilometers), or more than 100 times the distance between Earth and its moon. The astronomer points out, however, that the asteroid could potentially pass within 100 million miles of Jupiter, which may result in an orbital adjustment by the giant planet's gravitational manipulation.
Currently passing through the main asteroid belt toward the inner solar system, 2001 OG108 will make its next close approach to Earth in April of next year. As it zooms past Polaris in our northern skies, the asteroid will be bright enough for amateur astronomers to spot with moderately sized telescopes. Professional astronomers will likely take interest in this rare space rock as well, in order to study its composition and attempt to confirm its once-cometary nature.
46 visual observations give a preliminary uncorrected light curve of 10.2 + 5 log d + 5.9 log r, although this is a poor fit. This suggests that the comet should have been visible to visual observers long before February.
Observations in ICQ format, last observation 2002 May 15, updated 2003 February 2.
Lawrence notes that the object is diffuse with a nuclear condensation of diameter about 3". Following posting on the NEO Confirmation Page, P. Pravec and P. Kusnirak (Ondrejov 0.65-m reflector) confirmed its cometary appearance on CCD images obtained on Aug. 18.9 UT, and M. Kocer (Klet 0.57-m reflector) reports that the object is diffuse and at m_1 = 18.0 on Aug. 18.9. T. B. Spahr, Minor Planet Center, has also identified the object in data obtained by LONEOS on July 16.2. Full astrometry and parabolic orbital elements appear on MPEC 2001-Q18. [IAUC 7685, 2001 August 18]. The comet is distant and will not get any brighter.
V. A. Petriew (Cyprus Hills, SK). Round coma of diameter 3' with condensed nucleus and no tail. 0.51-m f/5 reflector at 80x. Motion about 2' to the southeast over an hour. Magnitude approximate. A. Hale (Cloudcroft, NM). 0.20-m Schmidt-Cassegrain reflector + CCD. Visual observations with a 0.41-m reflector on Aug. 19.47 showed a coma diameter of 2'.5 and m_1 = 11.0.[IAUC 7686, 2001 August 19]
Additional astrometry and orbital elements by B. G. Marsden, Smithsonian Astrophysical Observatory, appear on MPEC 2001-Q31. The eccentricity is very uncertain, and the orbit indicates a close approach to Jupiter in 1982. S. Nakano, Sumoto, Japan, has also computed an elliptical orbit and notes the similarity to the orbit of comet 103P. [IAUC 7688, 2001 August 21] The ephemeris suggests that the comet should have been within visual range since July, which suggests that either the comet has recently outburst (or has a steep light curve) or that the morning sky is not being well patrolled by amateur comet hunters.
From the SPA ENB 2001 August 27
In centuries past astronomers discovered new comets the old-fashioned way: they peered through telescopes or simply looked toward the sky, hunting for faint smudges that no one had seen before. It was hard work, but lots of people did it. Comets are named after their discoverers, after all, and finding a new one can mean instant fame. Hale-Bopp, Hyakutake and Shoemaker-Levy are just a few of the names we know ... because of comets.
But lately it seems just about every new comet is called "LINEAR" or "NEAT." Those are names, too, but not the names of humans. They're robots -- automated, computer controlled telescopes that scan the skies in a relentless search for near-Earth asteroids and comets. This year between January and mid-August such telescopes recorded 18 new comets, while humans had found none. Comet hunters -- the human kind -- just can't compete! At least that's how many beleaguered sky watchers have been feeling. But now Canadian amateur astronomer Vance Petriew has proved humans can still discover a comet the old-fashioned way.
Petriew was at the Saskatchewan Summer Star Party on August 18th when he turned his 20" telescope toward the Crab Nebula. Hopping from one star to another across the constellation Taurus, Petriew guided his telescope toward the famous supernova remnant -- but he never made it. He stopped instead at a curious smudge that appeared unexpectedly in his eyepiece. Thinking it might be a galaxy, he looked at his star charts to see if any were nearby, but there was no galaxy in the vicinity.
Petriew announced his comet discovery hours later, and since then astronomers have been monitoring the newfound comet to learn more about it. Based on data spanning less that a week, it appears that Comet Petriew may be travelling around the Sun once every 5.5 years following an elliptical path that stretches from a point just inside Earth's orbit (0.95 AU) out to the realm of the giant planet Jupiter (5.3 AU).
Says Brian Marsden of the Smithsonian Institution's Minor Planet Center: "We're still not completely sure of the orbital period, but Comet Petriew might have passed close to Jupiter in 1982 -- an encounter that could have nudged the comet into its current orbit." Before 1982 Comet Petriew's orbit was probably bigger than it is now. It couldn't have come so close to Earth in decades past, which might explain why it was never spotted before.
The comet should reach around magnitude 10.5 and then slowly fade as it recedes from our planet, as well as from the Sun. If the comet is well-behaved, it should remain brighter than 11th magnitude through mid-September. If it behaves like comet 103P, which continued brightening for nearly two months after perihelion, it could brighten to 8th magnitude in October.
The comet is a relatively easy object in the morning sky. Observing on August 27.12 with 20cm T x75 I made it 10.1, DC3 and 1.6' diameter, and in 14x100B it was 9.3, DC3 and 4.7' diameter. An observation in mid September suggested that it had changed little in brightness, however it is now fading and is likely to be fainter than 13th magnitude by the end of October.
36 observations give a preliminary uncorrected light curve of 10.7 + 5 log d + 15.5 log r
Observations in ICQ format, last observation 2001 November 17, updated 2002 June 24.
Further to IAUC 7689, D. Hammer reports astrometric measurements of a comet found by Chen Dong Hua on SOHO website images. The object was first detected on August 25.34 at mag 8.3 in LASCO C2 coronagraph images, moving southward from directly underneath the occulter; the comet brightened and showed a nice tail before entering the C3 field-of-view, where it began to fade, as indicated by the following additional V magnitudes provided by D. Biesecker and Hammer: Aug. 25.393 UT, 7.6; 25.463, 7.4; 25.977, 5.7; 26.102, 4.8; 26.221, 5.2; 26.227, 4.6; 26.446, 5.8; 26.811, 8.0. [IAUC 7694, 2001 August 28]
A. Lecacheux, N. Biver, J. Crovisier, and D. Bockelee-Morvan, Observatoire de Paris, on behalf of the Odin Team, write: "The H_2O 110-101 line at 556.936 GHz was observed in comet C/2001 Q4 on Mar. 6.6 UT with high spectral resolution (80 m/s). The line integrated intensity (main beam brightness temperature) was 2.7 +/- 0.1 K km/s over the 2-hr observation. This corresponds to a preliminary water-production rate of 1.3 x 10**29 molecules/s, taking into account opacity effects." [IAUC 8304, 2004 March 15]
C. E. Woodward, University of Minnesota; D. H. Wooden, NASA Ames Research Center; and D. E. Harker, University of San Diego, report 8-13-micron spectrophotometry of this comet on May 11.2 UT using the NASA Ames HIFOGS spectrometer at the Infrared Telescope Facility 3-m reflector: "Silicate-feature emission was observed with a flux-to-continuum ratio of 1.6, including emission from crystalline silicates at 9.3, 10.0, and 11.2 microns. The 10- micron peak flux was 1.6 x 10**-16 W cm**-2 micron**-1, and the observed N-band magnitude was -0.22 +/- 0.07. A blackbody fit to the local continuum yields a color temperature of 310 +/- 4 K." [IAUC 8339, 2004 May 13]
J. L. Wilde and M. L. Sitko, University of Cincinnati; and D. L. Kim and R. W. Russell, The Aerospace Corporation, report 3-13- micron spectrophotometry of comet C/2001 Q4 obtained on May 14.1 UT with the Mt. Lemmon 1.5-m University of Minnesota telescope (+ Aerospace Broadband Array Spectrograph System; 8".5 aperture; 51" chop throw; integration times 20 min on the comet and 10 min on the reference star, beta Gem): "A smooth comet continuum was seen to rise from 3 to 5 microns and from 7.1 to 8.4 microns, a little above the blackbody (about 310 +/- 5 K) that was fit to the continuum points on either side of the strong, structured silicate feature seen from 8.4 to 12 microns. This temperature is consistent with the temperature reported by Woodward et al. (IAUC 8339) but is dependent upon assumptions of where the silicate grain emissivity becomes much less than the emissivity of the (assumed) gray-body grains that emit the underlying contiuum. The grain temperature is about 9 percent higher than that of an equilibrium blackbody at the heliocentric distance of the comet. The continuum was fairly flat beyond 12 microns. The rising flux above the blackbody from 7 microns towards 3 microns may be due to scattered sunlight, thermal emission from grains with a mix of temperatures and optical properties, or both. Structure is seen in the silicate feature, but at slightly different wavelengths from those reported by Woodward et al. Here, emission peaks are seen at 10.5 and 11.2 microns, with no feature at 9.3 microns. The silicate-feature-to- continuum ratio was about 1.65, also consistent with the report by Woodward et al. With our aperture, the comet has narrowband (about 0.25 micron) magnitudes and combined random errors (due to calibration star and comet) of [3.5 microns] = 5.44 +/- 0.09, [4.5 microns] = 3.44 +/- 0.03, [5 microns] = 2.96 +/- 0.03, [8 microns] = -0.10 +/- 0.01, [10.5 microns] = -1.65 +/- 0.01, and [12 microns] = -1.72 +/- 0.03. The combined comet-and-calibration-star systematic intensity uncertainty is estimated at about 5 percent. The ratio of this brightness to that of Woodward et al. is consistent with a roughly linear dependence on aperture, or a 1/R radial grain-density dependence from the comet nucleus." [IAUC 8342, 2004 May 19]
J. Lecacheux, LESIA, Meudon Observatory; and E. Frappa, St-Etienne Planetarium, write: "We have observed the concentric dust shells of comet C/2001 Q4 with the Pic-du-Midi 1.05-m reflector during six 3-hr sessions from May 14 to 19, around the time of perihelion. Direct measurement of the radial expansion on consecutive exposures yields 163 +/- 20 m/s. From the measured 12000-km shell interval, a first approximation of P = 20.5 +/- 3 hr can be inferred for the period of nucleus rotation, suggesting the exclusion of any value shorter than 17-18 hr. Then by blinking images of the inner shell taken at 1-day or several-day interval(s), and assuming constant expansion velocity, we obtain a refined probable period P = 23.2 +/- 0.25 hr. We also followed a small dust jet rotating counterclockwise (facing the sun) on May 14; its estimated angular motion of about 16 deg/hr agreed with the above period. Fibrous-like features, not more 300 km wide, appear within the brightest shell at 10000-15000 km from the nucleus; they show a pure radial expansion and no other morphology change in 3 hr, and they recur in the following shell 0.9 day later. In fact, we observe a complex of 3 or or 4 muddled components (sub-shells), issued from so many active regions and with slightly different expansion rates." [IAUC 8349, 2004 May 31]
S. M. Brafford, University of Dayton; M. L. Sitko, University of Cincinnati; and R. W. Russell and D. L. Kim, The Aerospace Corporation, report 3-13-micron spectrophotometry of comet C/2001 Q4, obtained on May 31.2 UT with the Mt. Lemmon 1.5-m University of Minnesota telescope (+ Aerospace Broadband Array Spectrograph System; 8".5 aperture; 49" chop throw; integration times 10 min on the comet and 20 min on the reference star, alpha Lyr): "A smooth comet continuum was seen to rise from 3.5 to 8.4 microns, beyond which a strong silicate emission band was observed. An underlying blackbody continuum with a temperature of about 345 +/- 10 K was fit to the continuum flux at 5, 8.4, and 12 microns. This grain temperature is about 24 percent higher than that of an equilibrium blackbody at the heliocentric distance of the comet, and higher than that observed on May 14.1 (IAUC 8342) using the same instrument and telescope when the comet was closer to the sun. Structure is seen in the silicate feature, including emission peaks at 10.5 and 11.2 microns. The silicate-feature-to-continuum ratio was about 1.43 +/- 0.04, lower than that reported on May 14.2. No scattered solar flux was detected at the shorter wavelengths after subtracting the thermal continuum. With our aperture, the comet has the following narrowband (about 0.25 micron) magnitudes and combined random errors (due to calibration star and comet, as well as variations due to the presence of real spectral structure): [3.7 microns] = 6.8 +/- 0.3, [4.7 microns] = 4.60 +/- 0.11, [5 microns] = 4.27 +/- 0.06, [8 microns] = 1.71 +/- 0.06, [10.5 microns] = -0.54 +/- 0.02, and [12 microns] = -0.49 +/- 0.03 (the stated errors are standard deviations of the mean)." [IAUC 8351, 2004 June 11]
Further to IAUC 8351, W. J. Carpenter (University of Cincinnati), M. L. Sitko, R. W. Russell, and D. L. Kim report additional 3-13-micron spectrophotometry of C/2001 Q4, obtained on June 17.2 UT at Mt. Lemmon (integration time 45 min; reference star alpha Boo): "A smooth comet continuum was seen to rise from 3.5 to 8.4 microns, beyond which a moderate silicate emission band was observed. An underlying blackbody continuum with a temperature of about 305 +/- 5 K was fit to the continuum flux at 5, 8.4, and 12 microns. This grain temperature is about 16 +/- 2 percent higher than that of an equilibrium blackbody at the heliocentric distance of the comet. The silicate-feature-to-continuum ratio was about 1.26 +/- 0.02 -- lower than the values of 1.65 reported on May 14.2 (IAUC 8342) and 1.43 reported for May 31.2 (IAUC 8351). During the period of observation, the strength of the silicate feature above the continuum was unchanged. The crystalline olivine feature at 11.2 microns continues to be present with approximately the same contrast as orginally seen. With our aperture, the comet has the following narrowband (about 0.25 micron) magnitudes and combined random errors: [3.7 microns] = 7.75 +0.45/-0.33, [4.7 microns] = 5.68 +0.20/-0.17, [5 microns] = 5.61 +0.23/-0.18, [8 microns] = 1.96 +/- 0.10, [10.5 microns] = 0.43 +/- 0.03, [12 microns] = 0.15 +/- 0.02." [IAUC 8358, 2004 June 18]
Further to IAUC 8358, R. W. Russell, D. L. Kim, M. L. Sitko, and W. J. Carpenter, report additional 3-13-micron spectrophotometry of C/2001 Q4, obtained on June 20.2 UT at Mt. Lemmon (integration time 45 min; reference star alpha Boo): "A smooth comet continuum was seen to rise from 3.5 to 8.4 microns, beyond which a moderate silicate emission band was observed. An underlying blackbody continuum with a temperature of about 315 +/- 5 K was fit to the continuum flux at 5, 8.4, and 12 microns. This grain temperature is about 21 +/- 2 percent higher than that of an equilibrium blackbody at the heliocentric distance of the comet. The silicate-feature-to-continuum ratio was 1.32 +/- 0.02 -- slightly greater than the value of 1.26 reported on June 17.2 (IAUC 8358), but still significantly less than that reported on May 31.2 (1.43; IAUC 8351) and May 14.2 (1.65; IAUC 8342). The crystalline olivine feature at 11.2 microns continues to be present with approximately the same contrast as originally seen. With our aperture, the comet has the following narrowband (about 0.25 micron) magnitudes and combined random errors: [3.7 microns] = 7.73 +/- 0.17, [4.7 microns] = 5.49 +/- 0.20, [5 microns] = 4.95 +/- 0.23, [8 microns] = 2.10 +/- 0.18, [10.5 microns] = 0.50 +/- 0.05, [12 microns] = 0.26 +/- 0.04." [IAUC 8360, 2004 June 23]
C. E. Woodward and M. S. Kelley, University of Minnesota; and D. H. Wooden, Ames Research Center, NASA, report 8-13-micron spectrophotometry of comets 2001 Q4 and 2003 K4 1using the NASA Ames HIFOGS spectrometer at the Infrared Telescope Facility 3-m reflector: "Weak silicate-feature emission (cf. IAUC 8360, 8339) is present in the 10-micron spectra of C/2001 Q4 on July 28.24 UT, when the observed N-band magnitude (3" circular aperture) was 3.7 +/- 0.4. Preliminary analysis of the featureless 10-micron spectra of C/2003 K4 suggests that large amorphous carbon and silicate grains (radius approximately > 0.7 micron) dominate the coma. Further to IAUC 8361, no structure attributable to crystalline silicates was evident. The observed N-band magnitudes (3" circular aperture) of C/2003 K4 were: July 26.24, 3.6 +/- 0.4; 27.24, 3.4 +/- 0.2." [IAUC 8378, 2004 August 3]
Brian Marsden notes on MPEC 2004-K64 [2004 May 29] that
The "original" and "future" barycentric values of 1/a are +0.000042 and -0.000703 (+/- 0.000001) AU^-1, respectively. A somewhat comparable nongravitational solution, but satisfying 956 observations with mean residual 0".78, gives A1 = +1.18 +/- 0.04, A2 = -0.13 +/- 0.04.Brian Marsden further notes on MPEC 2004-L37 [2004 June 12] that
Non- gravitational parameters A1 = +1.49 +/- 0.03, A2 = -0.2965 +/- 0.0282 from 1106 observations .The "original" value of 1/a suggests that this is a new visitor from the Oort cloud.
Observations in early September 2003 put the comet at around 12th magnitude. Alexandre Amorim, observing on September 20.31 with a 0.14-m reflector x80 estimated the comet at 12.3 with a 0.5' coma. Observing with 20x80B in mid January Alexandre made the comet 8.9. By early February he was reporting it at 8th magnitude. I observed the comet from Stanley, Falkland Islands on February 19.03, where it was 40 degrees altitude and estimated it at 7.2 with a 9' coma. I flew to Rothera in the Antarctic the next day. On February 26.14 I was able to observe it in rather bright skies (sun 12 degrees below the horizon) and with a little cloud interference estimated it at 7.3 in 10x50B. On March 5.12 I had another view and made it a fraction brighter at 7.2. We then had a lengthy spell of cloudy weather, but with a forecast of clearing skies I arranged for an early morning call and made another observation on March 16.28. The comet was significantly brighter and I made it 6.9, with a 10' diameter coma. I left Rothera on March 19 and was able to make a couple more observations on the voyage to the Falkland Islands. We berthed at FIPASS just outside Stanley and from there is a short walk over a hill to dark skies. From here on March 25.00 I estimated the comet at 6.6 in 10x50B, with a 9' coma and 40' tail, and was also able to glimpse it with the naked eye at 6.0.
I observed the comet from the UK on May 10.8 and found it somewhat disappointing under rather hazy skies. In 20x80B it was 4.0, with a 15' DC5 coma and hints of a 0.8 degree long tail. Between May 16 and 23 I was staying at Hohenpeissenberg in the Bavarian alps and was able to observe the comet on several occasions. My first observation on May 16.8 put it at 3.5 in 10x25 binoculars, with a 2.7 degree long tail. By May 20.8 it had faded to 4.4, with a 1.5 degree long tail. It continues to fade very slowly, and by June 12.9 was 6.1, though still with a faint 0.5 degree tail. By mid August it had faded to 8.5, but was still an easy binocular object. By mid September it required a telescope, and I estimated it at 10.2 on September 18.92 in a 30cm reflector, however other observers were estimating it a little fainter.
Michael Mattiazzo gives the dates of the orbital plane crossings as 2003 April 21, 2003 Oct 24, 2004 April 20 and 2004 October 23.
1044 observations give a preliminary uncorrected light curve of 5.7 + 5 log d + 6.6 log r though it is currently about 1.5 magnitudes fainter than indicated by the mean curve.
Observations in ICQ format, last observation 2005 February 5, updated 2005 March 1.
Observations in ICQ format, last observation 2001 October 10, updated 2001 October 17.
Additional astrometry and preliminary parabolic orbital elements (from 25 observations, Aug. 28-29) appear on MPEC 2001-Q70. [IAUC 7698, 2001 August 29] The comet could reach 14th mag at high northern declination in October. This is NEAT's 15th comet and 13th this year.
Additional astrometry orbital elements, published on MPEC 2001-S06, indicate this comet (cf. IAUC 7698) to be of short period, with a period of 23 years. [IAUC 7722, 2001 September 21]
Visual m_1 estimates: Sept. 22.00 UT, 14.0 (K. Sarneczky, Agasvr, Hungary, 0.44-m reflector); Oct. 8.81, 11.8 (R. J. Bouma, Groningen, The Netherlands, 0.31-m reflector); 13.64, 11.9 (K. Yoshimoto, Yamaguchi, Japan, 0.25-m reflector); 14.74, 11.1 (Yoshimoto); 15.85, 11.4 (Bouma). [IAUC 7734, 2001 October 16]
44 observations give a rather unlikely preliminary uncorrected light curve of 5.5 + 5 log d + 41.0 log r, although this is a poor fit.
Observations in ICQ format, last observation 2002 January 13, updated 2002 October 1.
Improved orbital elements were published on MPEC 2001-S05, including prediscovery observations on Aug. 19 by LINEAR by B. G. Marsden and these indicate that this comet will pass only 0.014 AU from Mars on 2002 Jan. 10.7 TT, as first suggested by C.-I. Lagerkvist (Uppsala) and G. Hahn (German Aerospace Center, Berlin). [IAUC 7720, 2001 September 19]
Observations in ICQ format, last observation 2001 October 8, updated 2001 October 17.
Observations in ICQ format, last observation 2001 October 8, updated 2001 October 17.
M. Honda, University of Tokyo, and colleagues (T. Yamashita, H. Kataza, T. Miyata, T. Fujiyoshi, S. Sako, Y. K. Okamoto, T. Onaka, T. Sekiguchi, D. Kinoshita, and J. Watanabe) report on mid- infrared observations of two comets with the 8.2-m Subaru Telescope (+ COMICS). N/Q-band imaging of C/2002 V1 on Jan. 11.2 UT yield the following total fluxes within a 2".73-box aperture: 8.8 microns, 0.83 +/- 0.01 Jy; 11.7 microns, 1.55 +/- 0.02 Jy; 12.4 microns, 1.95 +/- 0.04 Jy; 18.8 microns, 2.79 +/- 0.06 Jy. Low- resolution (250) N-band spectroscopic observations (range 8-13 microns) of C/2002 V1 showed a broad amorphous silicate feature with a 11.2-micron local peak, indicating the presence of crystalline olivine. Total fluxes for C/2001 RX_14 on Jan. 11.6 (measured as above): 8.8 microns, 0.066 +/- 0.004 Jy; 12.4 microns, 0.279 +/- 0.016 Jy; 18.8 microns, 0.356 +/- 0.022 Jy. Low- resolution N-band spectroscopy of C/2001 RX_14 showed the possible shallow silicate feature, but no 11.2-micron local peak was found within the error bars. [IAUC 8053, 2003 January 16]
Brian Marsden notes on MPEC 2002-S05 that the "original" and "future" barycentric values of 1/a are +0.000776 and +0.000257 (+/- 0.000003) AU**-1, respectively. [2002 September 16] The "original value of 1/a suggests that this is not a new visitor from the Oort cloud.
The comet reached perihelion at 2.06 AU in January 2003 and reached 10th mag. Visual observers reported it at around 13th magnitude in early September 2002. It had brightened to around 12th magnitude by early November according to reports from Carlos Labordena and Jonathan Shanklin. Observations in January 2003 give magnitudes between 10 and 11.
116 observations received so far give an uncorrected preliminary light curve of m = 7.9 + 5 log d + 7.8 log r
Observations in ICQ format, last observation 2003 June 3, updated 2004 September 19.
S Nakano has identified the comet with 1979 O1, observed by Charles Kowal on three occasions between July 24 and 27 and then lost. The orbit was uncertain, but noted as possibly being periodic due to the low inclination.
CCD exposures taken by A. E. Gleason with the 0.9-m f/3 Spacewatch reflector at Kitt Peak on Nov. 26.4 UT show that the object 2001 RG_100 (discovered by LINEAR on 2001 September 12.26) is definitely a comet, showing a nuclear condensation of diameter approximately 6" and a tail 18" long in p.a. 265 deg. Following a request from the Minor Planet Center, J. Young reports that CCD images taken at Table Mountain on Nov. 27 show a 4" coma with a broad, faint tail extending approximately 12" in p.a. 265 deg. [IAUC 8244, 2003 November 28]
Further to IAUC 8244, S. Nakano (Sumoto, Japan) reports that comet P/2001 RG100 (LINEAR) is identical with C/1979 O1 = 1979h (Kowal; cf. IAUC 3395 and 3397; MPC 4904 and 4998), suspected at the time as being of short period but lost immediately after discovery. Nakano's improved orbital elements, given on Nakano Note 995, are very similar to those for the 2002 and 1992 epochs on MPEC 2003-W74, and he also gives elements for a 1981 epoch (T = 1981 Sept. 14). [IAUC 8247, 2003 December 2]
Following recovery in 2007 the orbit was refined to give perihelion distance at 1.06 AU on 2007 September 1.7 and a period of 5.85 years. It can pass 0.07 AU from the Earth and 0.1 AU from Jupiter.
The comet passed within about 0.1 AU of Jupiter in 1985, prior to which it was in a more distant, less eccentric orbit.
Observations in ICQ format, last observation 2002 March 12, updated 2002 October 1.
Brian Marsden notes on MPEC 2002-S07 that the "original" and "future" barycentric values of 1/a are +0.000998 and +0.001075 (+/- 0.000004) AU**-1 respectively. [2002 September 16] The "original value of 1/a suggests that this is not a new visitor from the Oort cloud.
Observations in ICQ format, last observation 2001 December 20, updated 2002 September 29.
An apparently asteroidal object of 19th magnitude discovered by LONEOS on November 17.27 and designated 2001 WF_2 (cf. MPEC 2001-W42) has been found to have a well-defined 45" tail in p.a. 320 deg on CCD images obtained on Feb. 13.5 UT by T. B. Spahr with the 1.2-m reflector at Mount Hopkins. Following notification by Spahr, C. W. Hergenrother also found a 27" tail in p.a. 320 deg and a stellar central condensation on a 1500-s co-added R-band image taken with the Catalina 1.54-m reflector. [IAUC 7827, 2002 February 13]
Brian Marsden notes on MPEC 2002-F19 [2002 March 18] that the "original" and "future" barycentric values of 1/a are +0.02285 and +0.001659 (+/- 0.000042) AU**-1, respectively. These values show that the comet is not a new one from the Oort cloud.
Observations in ICQ format, last observation 2002 February 11, updated 2002 October 1.
C. Hergenrother, Lunar and Planetary Laboratory; and K. Muraoka, Kochi, Japan, suggested a link between comet 11D (last seen in 1908) and P/2001 X3 (cf. IAUC 7778) -- a linkage confirmed at the Minor Planet Center and by S. Nakano (Sumoto, Japan). The orbital elements below are by Nakano (from 43 observations, 1908-2001, mean residual 0".8; nongravitational parameters A_1 = +0.13 +/- 0.01, A_2 = -0.0134 +/- 0.0007). The comet was not found in 1963 despite a prediction by B. G. Marsden (IAUC 1838, 1839, 1840). More recent predictions were made by Marsden and Sekanina (1971, A.J. 76, 1142), by Nakano (Comet Handbooks for 1989, 1995, and 1996, Oriental Astronomical Association; and NK 686), and by Muraoka (Comet Handbook for 2001, OAA). The indicated correction to Nakano's 2001 prediction (1998, NK 686) is Delta(T) = +3.4 days. [IAUC 7779, 2001 December 20] The comet was listed amongst those due to return in my predictions for 2001 in the BAA Journal for December 2000.
On 2001 Dec. 25, S. Nakano (Sumoto, Japan) reported that T. Oribe had apparently recovered comet P/1993 K2 (= 1993 XI = 1993l) the night before (December 24.86) with the 1.0-m reflector at the Saji Observatory. The position was within 2" of the prediction by B. G. Marsden on MPC 34423 (ephemeris on MPC 43696). No information was provided about the object's appearance other than m_1 = 19.5. The comet has now been independently reported by K. Sarneczky and Z. Heiner in 2002 Jan. 11 data obtained with the 0.6-m Schmidt at Piszkesteto, at m_1 = 20, but again with no information about the appearance. These observations confirm a tentative single-night detection by C. W. Hergenrother and D. Means of an object of stellar appearance (in an 840-s co-added exposure) at the comet's expected position a year ago with the Steward Observatory's 2.3-m reflector at Kitt Peak. [IAUC 7790, 2002 January 14]
Further to IAUC 7790, K. Sarneczky reports that his 300-s unfiltered CCD images taken on Jan. 11.2 UT show a diffuse, 8" coma and a faint, narrow, 13" tail in p.a. 283 deg. [IAUC 7792, 2002 January 15] Further to IAUC 7790, T. Oribe reports that his CCD images taken on 2001 Dec. 24.86 UT show a 0'.15 coma and an 8" tail in p.a. 295 deg. [IAUC 7794, 2002 January 17]
An apparently asteroidal object of 20th mag discovered by LINEAR on December 17.32 and designated 2001 YX_127 (cf. MPS 47220, MPO 24028) has been found to have a broad, fan-shaped extension in p.a. 100 deg on CCD images obtained on Feb. 14.2 UT by T. B. Spahr with the 1.2-m reflector at Mount Hopkins. Co-added CCD R-band images taken at about the same time by C. W. Hergenrother with the Catalina 1.54-m reflector show a 7" coma and a broad tail 8" long in p.a. 100 deg. [IAUC 7828, 2002 February 14]