New Comet Found the Old Fashioned Way

Don Machholz of Colfax, CA found his 11th comet on the morning of Tuesday, March 23rd. What sets Don’s 11 discoveries apart from the other comets found recently is the way it was found. Nowadays comets are found by computers analyzing thousands of digital images. Only after the computers have sorted through the data is there human intervention to confirm that the object being flagged as a comet is really a comet. Don, on the other hand, has found all 11 of his comets the old-fashioned way. With no help from computers or digital cameras, Don finds his comet by peering through his telescope and identifying faint fuzzies that shouldn’t be there. In fact, it is the first visual discovery of a comet since late 2006.

Comet C/2010 F4 (Machholz) is currently 11th magnitude. At this brightness, only observers with moderate-sized telescopes under dark skies will see it. Though the orbit is still somewhat uncertain, the comet appears to reach perihelion in early April at a distance of ~0.6 AU from the Sun. Unfortunately, it will not get much brighter. In fact, seeing it will only get more difficult as the comet moves closer to the Sun. Its increasing proximity to the Sun and the bright Moon now located in the morning sky means even advanced observers will have a hard time seeing it after a few days. It is possible the comet may only be observed for a week or so and then lost for the ages.

Orbit of Comet C/2010 F4 (Machholz) and the inner planets. Created with C2A. Credit: Carl Hergenrother/C2A.

The image above shows the orbit of the comet. With an inclination of ~90 degrees, its orbit is perpendicular to the orbits of the planets which is not unusual for a long-period comet. The big question is how was this comet missed by all of the professional asteroid/comet surveys. Nowadays most comets are found while very faint (17-19th magnitude) and a few years before perihelion. This comet probably escaped detection because it was located near the Milky Way for the past year. The Milky Way is so full of stars that the current crop of asteroid/comet surveys have a difficult time finding any objects there. As a result, many surveys avoid the Milky Way all together.

Congrats to Don Machholz! And thanks for showing us that persistence (he hunted for 607 hours since his last find in 2004) and old-fashioned comet hunting can still pay off in this era of computers and automation.

Meteor Activity Outlook for March 27-April 2, 2010

The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.

March is the slowest month for meteor activity. No major annual showers are active and only two very weak minor showers produce activity this month. The sporadic rates continue a slow decline as seen from the mid-northern latitudes and mid-southern rates reach a first half minimum. There is not much to look forward to this month expect for the evening fireballs that seem to peak this time of year from the northern hemisphere. This could be due to the fact the antapex radiant lies highest above the horizon this time of  year during the evening hours.

During this period the moon reaches its full quarter phase on Tuesday March 30.  At this time the moon lies opposite the sun in the sky and rises as the sun sets and sets as the sun rises. This weekend there is a small window of time between moonset and the start of morning twilight when the sky is favorable for meteor watching. The estimated total hourly rates for evening observers this week is ~1 for those in the northern hemisphere and ~2 for those south of the equator. For morning observers the estimated total hourly rates should be ~5 from the northern hemisphere and ~7 as seen from the southern hemisphere. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity.

Shower descriptions will be presented next week when the moonlight conditions
have improved.

The list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning.

Shower Name                RA     DEC   Vel     Rates
                                        km/s   NH    SH
ANT Antihelions          13h 20m  -09    30     1     1
ZSE Zeta Serpentids      17h 32m  -03    64    <1    <1
ZCY Zeta Cygnids         19h 40m  +38    44    <1    <1

RA - Right Ascension
DEC - Declination
Vel - Velocity relative to Earth (in km per sec)
Rates - Rate of visible meteors per hour from a
        dark site
NH - Northern Hemisphere
SH - Southern Hemisphere

Mar 20/21 to 25/26 Meteors

Nightly meteor rates remain low as there are no major active showers and the background Sporadic rate is near a yearly minimum. Rates were also depressed as a weak winter storm passed through the area, Though the storm only produced a few hundredths of an inch of rain, the clouds it produced affected observing for 3 nights.

Obs  Date(UT)      Time    TOT SPO ANT GNO ZSE
TUS  2010-03-26   09h 18m   7   7   0   -   0
TUS  2010-03-25   10h 05m   12  10  1   -   1
TUS  2010-03-24   06h 26m   6   6   0   -   0
TUS  2010-03-23   02h 58m   1   1   0   0   -
TUS  2010-03-22   08h 35m   5   4   1   0   -
TUS  2010-03-21   10h 13m   11  9   2   0   -

TUS - Camera in Tucson operated by Carl Hergenrother
SDG - Camera in San Diego operated by Bob Lunsford
TotTime - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions
GNO - Gamma Normids
ZSE - Zeta Serpendids

Mar 17/18/19/20 Meteors

Activity has been fairly consistent from night to night with anywhere from 10-16 meteors per night. Though a single minor shower, the Gamma Normids, is active none have been seen. This isn’t too surprising since this shower only produces a meteor or 2 per hour for observers who can see down to 6th magnitude. My cameras are much less sensitive than the human eye and can only see down to ~2nd magnitude. Also the radiant of the Gamma Normids is located in the far southern sky so it takes a rare one to be seen this far north.

The highlight of the past 3 nights was a bright short lived fireball seen on the evening of March 17 at 10.:51 pm (March 18 @ 5:51 UT). This fireball lasted for a little over 1 second but traversed only a small part of the sky. The whole event was caught by SALSA2, my small FOV zenith-pointing camera as well as the all-sky cam at  the MMT on Mount Hopkins. For some reason my all-sky camera did not record the event. Makes me wonder how many other bright meteors are being missed.

The video below is from the SALSA2 camera.

The next image is a screen shot of the all-sky camera at the MMT. This image is a ~10-second exposure so unfortunately we can’t get any video.

March 18 fireball from all-sky cam on Mount Hopkins. Credit: MMTO/SAO/Univ. of Arizona.

We can learn a surprising amount of information about this fireball just from the above images. The shareware program Fireball writen by Albino Carbognani (www.fis.unipr.it/~albino/ITASN/documenti/fireball.html) can be used to determine the trajectory through the atmosphere as well as an initial orbit.

Start Height = 71.7 km
End Height  = 67.7 km
Total Length of Travel = 15.7 km

Geocentric Velocity = 12.1 km/s

Semi-major axis = 0.82 AU
Eccentricity = 0.22
Inclination = 0.6°
Perihelion = 0.64 AU
Aphelion = 1.00 AU

The object  that caused the fireball was an Aten. This means it had crossed the Earth’s orbit and had a semi-major axis (its average distance from the Sun) less than 1.0 AU. The very slow geocentric velocity of ~12.1 km/s is almost as slow as a meteor can get (the slowest is 11.2 km/s, the fastest is ~72 km/s). The slow velocity is a result of impacting the Earth near the objects aphelion point. Note of warning, there is still much uncertainty in the positions and timing of this fireball. The orbit below is probably not exactly correct. Still, it is hard for this object to have been on an orbit other than an Aten with an aphelion near 1 AU. That much is certain. The perihelion distance, on the other hand, can be a few tenths of an AU larger or smaller.

Orbit of the Tucson fireball seen on March 18. Created with C2A and Fireball. Credit: Carl Hergenrother.

Obs  Date(UT)      Time    TOT SPO ANT GNO
TUS  2010-03-20   10h 16m   14  12  2   0
TUS  2010-03-19   09h 35m   16  14  2   0
TUS  2010-03-18   10h 19m   10  9   1   0

TUS - Camera in Tucson operated by Carl Hergenrother
SDG - Camera in San Diego operated by Bob Lunsford
TotTime - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions
GNO - Gamma Normids

Mar 15/16/17 Meteors

In the previous post I showed images of a bright fireball seen Sunday evening over Tucson. At the same time a bright fireball was seen in northern California. At first I wondered if the two might have been related, or even the same fireball. Thanks to recent analysis of video data in California by  the Sierra College, we have our answer. No, the 2 fireballs are not the same and also are not related. More info on the March 15 CA fireball can be found here.

Obs  Date(UT)      Time    TOT SPO ANT GNO
TUS  2010-03-17   10h 15m   15  13  2   0
TUS  2010-03-16   10h 07m   13  8   4   1

TUS - Camera in Tucson operated by Carl Hergenrother
SDG - Camera in San Diego operated by Bob Lunsford
TotTime - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions
GNO - Gamma Normids

Mar 13/14/15 Meteors

Talk about nights at different extremes. Two nights ago had to rank as one of the most boring nights of the past 2 years. Not only were a small number (6) of meteors seen by my deep camera, no meteors were seen by my wide-angle fireball camera. For a clear night you should see at least 3 or 4 bright ones.

Last night (Sunday, March 14) was better. What really set it apart was a bright fireball seen over Tucson at ~10:14 pm (5:14 UT). Both of my cameras picked it up. The first movie shows the very early stages of the fireball. Since the SALSA2 camera only has a FOV of about 50×70 degrees, this camera was lucky to see any of it. In the movie the fireball is moving nearly due north (north is to the bottom) and first becomes visible just to the north of Leo.

In the next view, we are looking at images from a camera with a much wider FOV. Here the fireball continues to brighten as it moves towards the North. It is still brightening as it moves out of the FOV (about 20-30 degrees elevation). The apparent skipping motion is due to my computer dropping frames. Guess I need a better system…

The near-all-sky cam on Mount Hopkins caught another view of the fireball. Hopkins is located to the south of my place so the fireball appeared further north.

MMT all-sky camera on Mount Hopkins. Credit: Tim Pickering/University of Arizona.

The fireball was also seen on all-sky cameras in Sierra Vista and on Mount Lemmon. Interestingly, a brilliant fireball was observed to the west of Sacramento, CA at almost exactly the same time. The jury is out as to whether the AZ and CA fireballs are one and the same since they could easily be unrelated. If anyone witnessed the fireball, especially observers to the north of Tucson, leave a comment and let us know. Let’s hope tonight brings another one.

Obs  Date(UT)      Time    TOT SPO ANT GNO
TUS  2010-03-15   10h 25m   13  10  3   0
TUS  2010-03-14   08h 47m   6   6   0   0

TUS - Camera in Tucson operated by Carl Hergenrother
SDG - Camera in San Diego operated by Bob Lunsford
TotTime - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions
GNO - Gamma Normids

Mar 5/6 to 12/13 Meteors

Now I’m finally caught up.

The winter rainy season is letting up for a weeks or so and my zenith pointing camera is finally bolted down (so no more mystery shifts which make astrometry difficult), so now we just need some nice meteor displays. Rates are low in March and should remain low for another month.

Obs  Date(UT)      Time    TOT SPO ANT DLE GNO
TUS  2010-03-13   10h 30m   8   7   1   -   0
TUS  2010-03-12   09h 52m   10  10  0   -   0
TUS  2010-03-11   00h 30m   1   1   0   -   0
TUS  2010-03-10   07h 26m   8   6   2   0   0
TUS  2010-03-09   07h 52m   8   8   0   0   0
TUS  2010-03-08   00h 00m   Bad Weather - No Meteors
TUS  2010-03-07   01h 54m   4   2   1   1   0
TUS  2010-03-06   04h 00m   9   7   1   1   0

TUS - Camera in Tucson operated by Carl Hergenrother
SDG - Camera in San Diego operated by Bob Lunsford
TotTime - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions
DLE - Delta Leonids
GNO - Gamma Normids
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