Waiting for U Sco

General astronomy-related discussion (publicly viewable)
User avatar
BobSikes
15+ Years Member
Posts: 426
Joined: Sat Jun 14, 2003 12:57 pm

Waiting for U Sco

Unread post by BobSikes »

The recurrent nova U Scorpii is going to blow! The only question is when. The prediction is ... now! Although it hangs out at only mag 17 and visible only to Commander Cosmos and the other devoted imagers, within 5 hours after the star system explodes it will reach mag 7 and thus visible in binoculars.

So put this on your observing list and let's see if an ASSNE member can be first to report the flare up -- both to the AASVO and on the ASSNE board! Here are some useful links.

A very nice article in Sky and Telescope describing this event - with finder charts -- by Dr. Brad Schaefer
http://www.skyandtelescope.com/observin ... 35242.html

A great interview with Dr. Schaefer on Slacker Astronomy.
http://www.slackerastronomy.org/wordpre ... iews-pt-i/
The actual interview starts about 19 min into the podcast.

The American Association of Variable Star Observer call for observations of U Sco
http://www.aavso.org/news/usco.shtml



The WebObs link where you will report any change in brightness
http://www.aavso.org/bluegold/
User avatar
BobSikes
15+ Years Member
Posts: 426
Joined: Sat Jun 14, 2003 12:57 pm

First Try at U Sco

Unread post by BobSikes »

Time: 11:45 EDT 5/10/2009
Location: In my second floor home office hanging out a south facing window
Equipment: 10X50 Celestron binos

The good news is that the field is really easy to find. I can put Beta Sco on the right side of the field and Chi Oph is on the other side.

The bad news is that with the nearly full moon just a fist width down, the limiting magnitude is about 6.5 (estimated with the three ~6.3 stars a little east of Nu Sco)

So I know the magnitude of U Sco is < 6.5 ... but then it always is.
:(

Someone pse turn off the Moon!
BobS
User avatar
BobSikes
15+ Years Member
Posts: 426
Joined: Sat Jun 14, 2003 12:57 pm

Try #2 -

Unread post by BobSikes »

U Sco Search #2
Date 5/12/2009
Time: 23:00 to 23:10 EDT
Equipment: 10X50 binos
Conditions: Clear and steady – Limiting mag ~ 8.3

Much better tonight. I could easily see all the mag 6-7 stars in the field NW of Chi Oph and the mag 8 stars (e.g. the mag 8.3 star just NNE of Chi Oph) were visible with a little averted vision. For my backyard, this is about as good as it gets. Especially since I’m again hanging out an upstairs window -- and partially blinded by an upward :x facing flood light in the apartment complex behind me -- to get the U Sco field to be above the trees by 11pm. I couldn’t resolve the mag 8.6 star (Hip 80403) that is almost due east and a half degree away from U Sco.

Using star HIP 80240 (on the top of the AASVO chart, 6.9 mag) and a pair of stars HIP 79984 (mag 7.0 ) and HIP 80061 (mag 7.8 ) that lie about 1 deg WSW (and off the AASVO chart) as my boundries, I can say confidently that USco has not reached mag 8.3 tonight.

Come on folks with darker sites and scopes. Has it hit mag 10, or 13 or 16 yet? :wink:
User avatar
Pete
Astro Day Coordinator
Posts: 3999
Joined: Fri Jun 13, 2003 9:03 pm

Going deep on a windy night

Unread post by Pete »

19:00 hrs, Sunday, May 10, 2009

Well, last night Bob Sikes whopped us with his U Scorpii challenge and tonight the sky is clear. Although it’s quite windy I’m up for the challenge. The scope’s set up with the f/6.3 focal reducer. It’s not as fast as the f/2.0 or f/3.3 setup, but I think that I can go deep with it if I just add time.

I get a lovely set of twilight flats: L flats both binned & unbinned, plus binned RGB and CLS.

Image

The wind’s pretty strong and seeing is poor. But let’s see exactly what can be achieved in the wind.

Scorpius won’t be up for hours yet, and there’s a full moon in Scorpius. So I’ll worry about U Scorpii later. Tonight’s first object of interest is galaxy M66. I’ve had a difficult time imaging this galaxy. One side of the image continually comes out overexposed. So exposure is limited to 25 X 60 seconds.
Image

Although it doesn't show in this, the second of 25 images, the result is the same. The left hand side continues to be overexposed. What the heck’s going on with M66? Or my setup? Or both?

Dwarf planet 38628 Huya is now ideally suited for viewing. The result of 10 X 300 seconds using the CLS filter just isn’t getting me to 17th magnitude. But maybe it’ll pop out in post processing.

Image

It didn’t.

It’s now 00:15 and Scorpius has climbed my neighbor’s roof and leaped for the sky. The moon’s only 10° from U Scorpii’s location so the CLS filter is a must. Here we go. 35 X 15 second binned 2 X 2 thru CLS.

Image

I’m just tickling 17th magnitude. And it’s just not enough.

Shut down & closed up at 01:00 hrs.

Conclusions & lessons learned:

Although I didn’t get nearly as deep as I’d hopped, it was a warm and pleasant evening. I suspect that the limiting factor as far as magnitude was the very bad seeing. The scope tracked very well and did not chase flickering images – probably because guiding was set at 2.5 second adjustment instead of every 2 seconds.

The uneven illumination on the M66 frames is a puzzlement. I don’t have any extraneous light hitting the corrector plate. And I don’t get this offset light on any of the other images. The next test is to rotate the camera and see if the lighted region stays in the same area of M66 or rotates with the camera.

After reading the AASVO observing manual it appears that without the V photometric filter CCD photometric data is pretty worthless. So I’ve a Schuler-AstroDon V filter on order.

There’s crud coming at us, but tonight’s forecast looks pretty good. It’ll be an early night but I do plan on taking another shot at M66 and Huya. No V filter yet, so that’s my excuse to pass on U Scorpii.

Pete 16:53 hrs. Wednesday, May 13, 2009
Pete P.
User avatar
BobSikes
15+ Years Member
Posts: 426
Joined: Sat Jun 14, 2003 12:57 pm

Imagers In Action!

Unread post by BobSikes »

Great job Pete! U Sco < mag 16 was confirmed until 1:00 when you shut down.

And while you are correct that the best data for U Sco will be taken with the V filter, should a dot appear where U Sco is now not, that's brighter than the mag 16 stars, with or without filters, AASVO and astronomers all over the planet want to know ASAP, so they can slew over and see what's going on.

Another point. Pete is now set up as a primo first alert observatory. But, Pete has to sleep. From the the time from when Pete would be able to see U Sco passing mag 16 to the time it would pass the mag 12 stars that surround it in his image is no more that an hour. And any 8" scope would pick U Sco crossing mag 12 visually without much trouble.

The more ASSNE eyes on the object, the more likely one of us will be first to spot the rising phase and save the planet!

Well, ok not save the planet, but make an important contribution to the professional astronomical community. And get lots of fava beans.

BobS
User avatar
Rotorhead
Life Member
Posts: 2177
Joined: Thu Dec 16, 2004 10:30 pm

Unread post by Rotorhead »

Pete, I won't steer this thread too far away from U Sco, but in consideration of your query about M66, could you be seeing the core of the galaxy, which is considerably off center since this galaxy is distorted by the other Leo triplet members? The core and a large starburst area are to the left of center in the galaxy as it sits in your image. After you process it, open another thread and let's analyze M66...
Bob M
15" f5 Starsplitter Dob/80mm Finder
5" Explore Scientific triplet APO on a Vixen Sphinx GEM
________
"He numbers all the stars, and calls each one by name." Ps 147:4
User avatar
AstroGeek
15+ Years Member
Posts: 1090
Joined: Fri Jun 13, 2003 8:39 pm

Unread post by AstroGeek »

NO fava beans for me :(

Just before closing up shop last night, I decided to make a run at U Scorpii to see if anything was brewing. Thanks, Bob, for making this an intriguing object to watch. Some high thin clouds were in the area and, as usual, this object is quite low in the sky.

Here is a summary of what I could detect:


Image


Dan Silva and I found a neat AAVSO webpage in which members can upload their current magnitude estimates. Several postings are made each day and it still seems to be lingering in the VERY faint 18th magnitude range. As you can see, some observations just say "<14th mag" as U Sco hides beyond the observers light-grasp.

http://www.aavso.org/cgi-bin/newql.pl?n ... utput=html

So everyone, PLEASE let me know if there is news of a burst and I'll take pictures. At least for now we have a baseline pic.
User avatar
Pete
Astro Day Coordinator
Posts: 3999
Joined: Fri Jun 13, 2003 9:03 pm

Unread post by Pete »

By golly, you got it Steve. Good show!

I've had a photometric V filter on order for more than a week, as AAVSO would puke all over me if I reported unfiltered results. Did some testing on M94 last night and found that my problem is in the camera, and not related to cooling. So I'm shut down for a while.

Pete
Pete P.
User avatar
BobSikes
15+ Years Member
Posts: 426
Joined: Sat Jun 14, 2003 12:57 pm

Mag 18 and holding

Unread post by BobSikes »

Nice work Steve. And good idea too. Should anyone observe, or even just notice that USco has erupted on the AASVO or other web pages, fire off an email to Steve, Dan, Pete, Ed, Manny etc. the ASSNE imagers and get some shots of the increase. For art vs science, no need for a V filter. The relative change is good enough.
User avatar
WCGucfa
Posts: 1856
Joined: Mon Apr 17, 2006 1:39 pm

Unread post by WCGucfa »

Gee, I knew if I didn't post for awhile I would be dropped as an IMAGER. :cry:

Bill :wink:
Comets:40, Best Meteor shwr: Leonids '01, Best Aurora:Oct. '03.
Total.Sol.Eclipse,7/10/72 from Nova Scotia.Annular Sol. Eclipse '94,
Trans.of Venus 2004&2012.,ShoeLevy crash into Jupiter '94.
4/25/66 fireball-9 mag.,SN2011fe,N2012aw,DelphN2013.
Post Reply