30 May 2020 comet & asteroids & supernova search

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30 May 2020 comet & asteroids & supernova search

Unread post by Pete »

Saturday, 30 May 2020

In the low 80s today so the dome’s opened before dinner for cooldown. Tonight’s objectives are to do some astrometry and to search for a supernova. It’s 69° at the start of the night. And there’s a 1st quarter moon high in the south. Refined alignment on Spica.

Asteroid 137199 is a 3 km sized Amor now a bright 16.3 magnitude and suitable for twilight observing. Motion is 3.3’/hr. Imaging initiated at 20:52 hrs: 1 minute exposure, 2X2 binning, -15°C cooling, 1 Hz guiding. (Actually it’s still a bit warm and the camera’s only cooling to -13.5. But that’s close enough.) As the sky darkens the first workable image comes in at 21:01 and the set’s complete at 21:08 hrs. Frames 1, 2 & 3 show ∆RA & ∆Dec = 0. S/N is 11/1 and FWHM 4.3” Photometry reported as 16.0 magnitude.

Comet C/2017 T2 PANSTARRS might be anywhere between 8 and 10 magnitude tonight. It’s 1.7 AU from Earth and moving at 2.2’/hr. Imaged from 21:29 – 21:40 at 1 min, 1X1 binning, -15°C cooling, 1 Hz guiding. Fames 1, 3 & 5 show ∆RA = -0.1’ & ∆Dec = 0. Cannot properly measure comet S/N or FWHM or magnitude. 10 X 1 minute:

Asteroid 184990 is a 3.5 km sized Apollo now 17.4 mag and 0.5 AU distant. Motion is 3.5’/hr. Imaged from 21:53 – 22:01 at 90 seconds, 2X2 binning, -15C cooling, 3 Hz guiding. Frames 1, 2 & 3 show ∆RA & ∆Dec = 0. S/N is 14/1 and FWHM 4.7” Photometry reported as 17.0 magnitude.

Asteroid 68350 is a 4 km sized Amor now 18.8 magnitude and 1.2 AU from Earth. Motion is a slow 54”/hr. A problem is being experienced with the Guide 9 to telescope interface and slew commands are being refused as being “below limiting altitude”. Not true. Slewed using scope hand paddle and the problem went away in subsequent slews. Imaging initiated at 22:28 hrs: 3 min, 2X2, -15C, 1 Hz. Frames 1, 2 & 3 show ∆RA & ∆Dec = 0. S/N is 8/1 and FWHM 3.5” Photometry measured at 18.5 magnitude but not reported as the S/N is low and the measurement not trusted.

Now the most unique part of the evening – searching for a supernova. These suckers are normally detected within galaxies. One was discovered in M61 just 2 weeks ago. I’ve been unsuccessful with comparing my images to someone else’s imaged, but I do have the NGC 3184 frame from May 13th. Four 5-minute images run from 22:56 – 23:11 with 1X1 binning, -15C cooling, 1 Hz guiding.

Alignment’s pretty critical. The two fields of view must overlay very closely. Takes a few extra minutes.

Astrometrica has ability to both stack and blink. But overlaying stacked images resulted in cosmic ray hits showing up and getting confused with supernova. At least 2 frames from each date must be available for comparison as even with single frames there may be a random cosmic ray hit. Wound up comparing one of tonight’s images against a couple from the 13th before I got satellite trails and cosmic ray hits out of both frames.
So here we go, doing a blink comparison from the 13th and the 30th:


Nope. No big discovery here. But lots learned.

In at 23:33. It’s still a warm 64°F. During the 5 minute NGC exposures I transmitted 12 observations to the MPC.

Conclusions & lessons learned:

Supernova search is probably the least complex astro science that can be done, and a lot of college observatories use these as student astronomy class projects. But it fails to turn me on. Perhaps because chasing asteroids is a lot more interactive.

Pete P.
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Re: 30 May 2020 comet & asteroids & supernova search

Unread post by Paul D »

Very interesting report Pete. I always enjoy reading your reports.

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Re: 30 May 2020 comet & asteroids & supernova search

Unread post by AstroGeek »

Love it, Pete. Keep posting your observations.
Steve L
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