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C/2019 Y4 (ATLAS)

Posted: March 20th, 2020, 6:11 pm
by Christopher K.
Today there are general media outlets reporting that Comet ATLAS may shine as bright as the Moon later this spring. I notice the headlines don't specify Full Moon or the Moon at another phase. That ambiguous reporting is a little irresponsible. it is true, ATLAS is brightening somewhat faster than predicted but not too much. If we are fortunate, ATLAS may brighten anywhere from magnitude 2 to 0--to magnitude -1 if we're really lucky. It just moved into Andromeda a couple of nights ago.

However, this is one of those teachable moments. We need to get rid of some of this light pollution right now, as honestly we never know when we'll need a natural sky to see a pleasant surprise like a fairly bright comet.

More information: ... 019_Y1.pdf

Here's an image from the first week in March... ... -y4-atlas/

Re: C/2019 Y4 (ATLAS)

Posted: March 21st, 2020, 6:52 pm
by Christopher K.
ATLAS is currently about nine light-minutes from Earth--1.62 billion kilometers (if my math is correct). It seems to share the same path as the Great Comet of 1844. Does that mean the 1844 object and ATLAS were once one large comet that broke apart?

A nice image from Rolando Ligustri:

Re: C/2019 Y4 (ATLAS)

Posted: March 29th, 2020, 11:21 pm
by Christopher K.
Wow. Bob King is reporting that ATLAS is brightening "exponentially". Alastair Ling seems even more excited. We should be cautiously optimistic--comets are notorious for teasing skygazers with possible brilliant apparitions only to shine feebly or even break into pieces.

More information: ... ye-object/ ... -naked-eye

Re: C/2019 Y4 (ATLAS)

Posted: April 8th, 2020, 4:52 pm
by Christopher K.
Some were saying it was too good to be true. ATLAS may be breaking up. Current images and observations show its nucleus is elongating which is not a good sign. Still if we're lucky it may still reach magnitude 4, or magnitude 2 if we're really fortunate. If you have a telescope you'll probably confirm that ATLAS is about 8.0 right now. Sadly, a binocular will not be useful unless you've taken steps to preserve or reacquire a natural contrast sky.

Here is the forecast for 9pm CDT...
precipitation potential, 2%
sky cover, 36%
relative humidity, 85%
temperature, 25˚C
surface wind, SW 10 km/h

Danko's Clear Dark Sky states that during HRPO's viewing time the transparency rating will be "below average" (2 out of 5) and the seeing rating will be "poor" (2 out of 5). This is a good forecast.

More information: ... ye-object/

Re: C/2019 Y4 (ATLAS)

Posted: April 11th, 2020, 8:17 pm
by Christopher K.
While it lasted ATLAS proved to be an excellent subject for photography. Rolando Ligustri captured the visitor in the same frame as the galaxy pair M81 and M82...

This situation is proof positive that we should grab our first possible sighting of a comet as soon as we can, and we should demand dark skies as much as we can.