Asteroids and Comets Special Interest Group

About This SIG

Communications to or within the group will be made by direct e-mail or, for those who do not have internet access, by snail-mail or phone. Initially we will discuss individual objectives, individual expertise and facilities, techniques, information resources, group observing, and whatever else may interest group members.

AAAP members wishing to join this SIG should inform the Chair by direct e-mail (not through the Listserver), snail-mail, or phone.


Truman Kohman
1300 Bower Hill Road, Apartment 1430, Pittsburgh, PA 15243

Asteroid Charts

For preparing finding/tracking charts for asteroids I use Guide 7.0. This is a fantastic charting program, available from Project Pluto with many features. One feature is a complete data base for bright asteroids.

First I prepare a chart at level 3 (45 degrees - N-S, somewhat greater E-W) with the star limit set at magnitude (e.g.) 6 and the asteroid limit set at magnitude (e.g.) 12, and centered on the ecliptic at about 180 degrees from the Sun. This shows what asteroids are visible at the specified limit around midnight. One can also prepare charts centered at about 120 and 240 degrees from the Sun to show asteroids visible earlier and later in the evening.

Then I select an asteroid, or perhaps two close together. I click on the asteroid, or between the two, to center the field there. I then change to level 5 (10 deg) or 6 (5 deg). I set the time to the first of the month (or other desired beginning time). I then add a track for the/each asteroid with interval 1 day, number of steps equal to the number of days in the month (or other desired period), with ticks each (e.g.) five days.

I now change level if desired, center the chart so that at least one track is entirely within the chart, and so that there is at least one easily located bright star to serve as a starting point for star hopping. I set the RA and DEC scales with markers and labels at 5 min and 1 deg and set the star magnitude limit a little fainter than the asteroid(s) will be during the month. The starting magnitude(s) can be found by right-clicking the position(s). The ending magnitudes can be found by temporarily changing the date to that at the end of the tracks.

I then print the chart. With a black marker I add the asteroid name(s), the dates on the tracks, the designation(s) of the bright star(s), the magnitudes at the beginning and ends of the track(s) (in circles to tenths without decimal(s)), and other useful information.

For my own use, this is as far as I go. If I wish a digital version, I scan the chart, crop it a little, and save it in .bmp, .jpg, or .gif format.

The chart then lets one use it for looking for the asteroid(s) any time during the month (or for the duration of the tracks).

Current Asteroid Charts

This month we feature two main-belt asteroids in nearly parallel paths as they pass through opposition in Ophiuchus in April.

20 Massalia

At opposition June 11 at magnitude 9.9. During the month it will brighten from magnitude 10.2 to 9.9 and then fade to 10.4.

49 Pales

At opposition June 9 at magnitude 12.6. During the month it will brighten from magnitude 12.9 to 12.6 and then fade to 13.1.

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Current Comet Chart(s)

This month there are seven comets brighter than magnitude 14. However, some of them will be difficultly visible or not visible in the Northern Hemisphere during June.

C/2006 Q1 (McNaught)

This comet was discovered in 2006 August by the prolific comet discoverer R. H. McNaught of the Siding Spring Observatory in Australia. Its orbit is parabolic and it will come to perihelion on July 4 of this year. It was at perigee on April 8. Magnitude estimates in May yield an absolute magnitude of 4.7, slightly brighter than last monthÕs 5.1. According to this it will be close to ~11.3 in apparent magnitude all June. It will be moving NE from Hydra through Sextans into Crater and visible low in the SW during and after evening twilight.

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C/2007 W1 (Boattini)

This comet was discovered on November 20, 2007, by Andrea Boattini during the course of the Mt. Lemmon Sky Survey in Arizona. He has discovered (or co-discovered) up to 170 asteroids, and Comet C/2007 W1 was his first comet discovery. Its orbit is parabolic and it will come to perigee on June 12 and perihelion on June 24. Magnitude estimates in late May and early June give an absolute magnitude of 8.8, fainter than last monthÕs 8.0, according to which its apparent magnitude will brighten from ~5.5 to ~4.8 and then fade to ~5.4 in June as it moves WNW from Pupis through Canis Major and Lepus into Eridanus. Unfortunately, it will be above the horizon only during daylight hours.

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C/2008 A1 (McNaught)

This was another discovery of R. H. McNaught, who is the discoverer or co-discoverer of 40 comets, this one on 2008 January 10. Its orbit is parabolic. It will come to perigee on September 3 and perihelion on September 29. Magnitude estimates in May yield an absolute magnitude of 5.2. In June it will brighten from apparent magnitude ~10.4 to ~9.2 as it moves ESE from Columbia into Pupis. It will reach ~6th magnitude in September. Now it is very far south and it too will be above the horizon only during daylight hours.

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C/2008 J1 (Boattini)

This is the second comet discovery by Andrea Boattini of the Remanzacco Observatory in Italy, during the Catalina Sky Survey from Mount Bigelow in the Catalina Mountains in Arizona. It was discovered on 2008 May 2. Its orbit is essentially parabolic. It will come to perigee on 2008 June 20 and perihelion on July 13. Magnitude estimates (May and early June) yield an absolute magnitude of 9.0, so it will be close to apparent magnitude ~12.3 all June as it passes N through Cygnus into Cepheus. It is nearly circumpolar and visible most of the night.

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P/2008 J2 (Beshore)

This comet was discovered by Edward Beshore, also during the Catalina Sky Survey, on 2008 May 6. It is periodic with a period of 6.50 years. It came to perihelion on 2008 March 20 and perigee on May 30. Magnitude estimates (May and early June) yield an absolute magnitude of 8.8, according to which it will be close to apparent magnitude ~13.6 all June. It will be moving SW in Ophiuchus. It will be visible in the SSW during the early morning.

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This comet was discovered in 1892 November by British amateur astronomer Edwin Holmes (1842-1919), at which time it was of visual magnitude ~4. It had just flared from its expected magnitude ~16. In the following week it faded to magnitude ~7 but then had a second outburst before it disappeared. After spotting it again in 1899 and 1906, astronomers lost track of it until 1964. Its period is about 6.9 years. Last year it was at perihelion on May 4 and at perigee on November 6. It was observed as 14.5 mag in July, and then it continued fading down to 17 mag until mid-October as predicted. Then a great outburst occurred on October 23, and it became as bright as ~2.5 mag in the fall, visible with naked eyes, but best seen in binoculars. It started as a bright fuzzy patch, but has grown much larger and its surface brightness has become quite faint. The latest magnitude estimates (late March and April) give an absolute magnitude of -1.9, the same a s last month. According to this it will fade in apparent magnitude from ~6.5 to ~6.8 as it moves ESE from Auriga into Gemini in June. It will be low in the NW in the evening twilight.

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