Chasing Comets

C/2017 O1 (ASASSN)

My first comet ever seen was C/2012 ISON, back in 2013 from Colombia, and my first comet seen from China was  C/2014 Q2 Lovejoy, both in binoculars. ASASSN1 has some significance because it

Click to enlarge image

is my first comet seen in the US. This was the first comet discovered by the All-sky Automated Survey for Supernovae (ASASSN) on the last 19th of July.  This year, it was expected to reach maximum brightness (around magnitude 9.3)  by mid October when it reached perihelion at around 108 million kilometers from Earth, beyond the orbit of Mars.  

Last 13th of October, friday night, I set up the scope early with the purpose to catch ASASSN in the first hours of Saturday. I had to wait until the constellation of Perseus would make its way through the giant trees around, but also I wanted to avoid the moon glance, to keep the sky as dark as possible.  However, Stellarium was reporting this comet as magnitude 12.05, so I was a little skeptical about being able to reach it with the telescope.

When Perseus had gotten up at a good altitude above the trees at 2 in the morning,  I aimed the scope at bPer with the red dot finderscope and then went to the RACI view. From there, I went down looking for the comet and suddenly stumbled into a lovely parallelogram made by 4 stars; HIP 21972 was the brightest of all.  Once I had landed there with the RACI, I went to the 40mm eyepiece eyepiece. To look for comets and other dim stuff I rather prefer to hunt with a low magnification eyepiece and my hunter is the 40mm Celestron Omni.  What I saw through the eyepiece view was the comet: a dim central stellar core sorrounded by a fuzzy bluish/gray halo.  The core was as dim as the closest star, reported in Stellarium as magnitude 11.20 so I estimated the core to be at 11th magnitude too, information that matches with the report for that date in the website of sky live.

With the Comet in middle of the FOV, I decided to try more magnification, so I tossed the 15mm Luminos eyepiece on to see what it could reveal. The core was almost gone, but two tiny background stars appeared close to the comet’s core. With averted vision I thought I saw traces of a tail of the comet, but I could not confirm them later. I finally decided to perform a sketch of the area using the lowest magnification possible and the sketch featured is a result of that sketch processed in photoshop.

If the sky is clear, this is a good time to search for ASASSN because lunar phases are heading to New Moon.

Good hunt!

LG

Edited by: Jennifer Steinberg (editor in chief)

Sources

theskylive.com

cometchasing