Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 01/17/2023 - 23:14
AAVSO Alert Notice 809 announces an observing campaign on the YSO AB Aur beginning immediately. Please see the notice for details and observing instructions.
There are threads for this campaign under the following AAVSO forums:
- Campaigns & Observation Reports: https://www.aavso.org/ab-aur-campaign-2023
- Young Stellar Objects: https://www.aavso.org/ab-aur-campaign-2023-01
Please subscribe to these threads if you are participating in the campaign so you can be updated. Join in the discussion or ask questions there!
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
See comment listed below
I've just started using my Ha filter and wanted to participate in this but also didn't want to upload data that was incorrect. How can I tell if my data is in the ballpark. I just pulled a couple of images, stacked them and ran the report using stars 116 and 120 as specified and came up with a magnitude of 8.959. I'll be submitting B,V, and Ha data every couple of days. But again, I didn't want to populate the database with erroneous data. Err was .0001 with a SNR of 766.
I just did a quick…
JM,
I just did a quick check of my images from last night and I get the following numbers.
B = 7.235
V = 7.093
Ha = 6.654
These are before stacking and won't be what I ultimately submit but wanted to at least be able to give a little preliminary feedback. My checkstar numbers for the 120 star are pretty close to the AAVSO numbers so my magnitudes above I think are decent. Is it the Ha filter that you get 8.959?
One possible explanation is that AB Aur is overexposed in your images and so shows up fainter in your photometry. That said, the S/N of 766 doesn't like overexposed.
What magnitude do you get for the check star?
-Walt Cooney (cwt)
Thanks for the help and values. Just looked at my last night results and they are very close to your observations. Not sure what the problem was but I'll just have to watch the future observations closely.
Terrific. Thanks for update.
-Walt
I have taken images with ITelescope T24 and HA_3nm narrowband filter. The HA values are about 0.3 magnitudes brighter than with my own measurements with HA_7nm narrowband filter. Has anyone made similar experiences, or do I still have an error in my evaluations?
Thanks
Gerd
AAVSO Alert Notice 811 reports on the exact times of HST observations of AB Aur and has an important note about which check star to use. Please see the notice for details and observing instructions.
There are threads for this campaign under the following AAVSO forums:
- Campaigns & Observation Reports: https://www.aavso.org/ab-aur-campaign-2023
- Young Stellar Objects: https://www.aavso.org/ab-aur-campaign-2023-01
Please subscribe to these threads if you are participating in the campaign so you can be updated. Join in the discussion or ask questions there!
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
Hi folks. Dr. Biddle tells me that the Feb 7 and 8 run on AB Aur was successful and the next HST visit will be March 1 and 2.
Clearest skies,
Walt Cooney (cwt)
AAVSO Alert Notice 814 reports on the exact times of the second set of HST observations of AB Aur. Please see the notice for details and observing instructions, including information about which check star to use.
There are threads for this campaign under the following AAVSO forums:
- Campaigns & Observation Reports: https://www.aavso.org/ab-aur-campaign-2023
- Young Stellar Objects: https://www.aavso.org/ab-aur-campaign-2023-01
Please subscribe to these threads if you are participating in the campaign so you can be updated. Join in the discussion or ask questions there!
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
AAVSO Alert Notice 814 reports on the exact times of the second set of HST observations of AB Aur. Please see the notice for details and observing instructions, including information about which check star to use.
There are threads for this campaign under the following AAVSO forums:
- Campaigns & Observation Reports: https://www.aavso.org/ab-aur-campaign-2023
- Young Stellar Objects: https://www.aavso.org/ab-aur-campaign-2023-01
Please subscribe to these threads if you are participating in the campaign so you can be updated. Join in the discussion or ask questions there!
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
Dr. Lauren Biddle asked me to share this update with you:
AAVSO Alert Notice 842 announces a new observing campaign on the YSO AB Aur beginning immediately. Please see the notice for details and observing instructions. The notice also contains information about a free webinar on this star and campaign being held on November 19.
There are threads for this campaign under the following AAVSO forums:
- Campaigns & Observation Reports: https://www.aavso.org/ab-aur-campaign-2023
- Young Stellar Objects: https://www.aavso.org/ab-aur-campaign-2023-01
Please subscribe to these threads if you are participating in the campaign so you can be updated. Join in the discussion or ask questions there!
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
I don't see the comp 104 on the map for AB Aur, but the check star 120 is there. Can I use 116 which is just to the north west of AB Aur?
104 is a ways out. More than 10' I recall. I believe the webinar is on U-tube now. They discussed using 116 if you can't see 104.
I can see it but need to move off center to do it.. Good luck.
Ray
Hi
I have started off supporting this campaign with a night of 5 Ha images 'spaced out over the night' as suggested in the Webinar. For each of the 5 Observations, I captured 11 exposures which I then inspected prior to aligning and combining them. In several of the groupings of 11 images I found several images where the target was nearly saturated. I deleted these from their respective groups and proceeded to align and average-combine the 5 sets of images.
Now, I realize that, since each average-combined image, has a different number of 'source' images, the five final images are showing up in the fits header with different amounts of total 'luminance exposure time'. In creating the combined image, the' average' intensity of each image was used. Still, I wonder if having 6 images combined into one observation, 9 in another observation, 10 in the third and 11 in each of the remaining two observations, isn't somehow skewing the final data independent of whats going on with the target.
Could someone(s) set me straight on whether the above process is ok or whether my concern is correct and the image count needs to be the same for each group? If it is, I'd need to remove images from each group so that each group ends up with the same image count. Then, in order to ensure the SNR of comp and check stars, I'll need to considerably bump up the starting number of images for each observation. If I need 11 to be combined into the final image for each observation to ensure the SNR,
For example, say I have taken 15 source images for each of 10 observations spaced over the night. If I find 3 saturated images in one observation, I'd need to delete them from that observation stack and then delete the same number of images from every other observation to keep the final 'combined' images all with the same luminance exposure time exposure time. So my question boils down to - ' does equalizing the image count for each final stacked image, really matter?'
Thank you for helping me out with this question.
Gary
Hi Gary. No need to make the image count in your image sets exactly the same. If you have to cull a few images in an image set, you lose the advantage of the extra signal from that image but it doesn't skew the data. It just means the error bars for that image set are a little wider. If you are close enough to saturation where you have some sub-images near saturating, I'd back off the exposure time for all the subs. Better not to push it right to the edge on that. Take more shorter subs instead and save yourself the trouble of going back through them and culling. Thanks for all your work contributing to the campaign!
-Walt
Hi Walt
You are batting 1000 so far so perhaps you can help with the following:
After reporting some Ha observations today, I noticed what seems might be an inconsistency between the Alert 842 information on the Check Star reference magnitude, stated at R=11.483, versus the VPHOT reference value of 11.382. Is this an issue or am I misunderstanding something?
Thank you for any clarification…
Gary
Hi Gary. I'm no longer batting 1000. You found a mistake and it's mine. There are multiple "120" stars in the field of AB Aur. When I was helping out with writing the Alert, I identified the correct check star by catalog name but then grabbed the Rc mag from one of the other 120 stars in the field mistakenly. The correct check star is GSC 2387-0935 (AUID 000-BPN-255) and its Rc magnitude is 11.382 as you point out. I'll contact the AAVSO staff and ask them to fix that. Thanks for finding this!
-Walt
Walt,
Just a nit but there seems to be a typo in Elizabeth's update today ... I believe the second sentence should say "check star" not "comp star". Just want to make sure there's no confusion.
Notes: In the original version of this Alert Notice, the Rc magnitude of the check star was in error. The correct Rc magnitude for the comp star is 11.382. - Elizabeth O. Waagen, December 12, 2023
I'm working on uploading several nights of Ha time series, excited to contribute. Thanks to you and others here for the helpful guidance.
Daniel Bailey (BIY)
Yes, my apologies for confusing the issue. The corrected Rc magnitude of 11.382 is indeed for the CHECK star. I have fixed the note at the top of Alert Notice 842.
Good observing,
Elizabeth
Apologies for not…
Hi Walt
Apologies for not asking in the webinar, but do you want observations reported individually or as a 'time series'?
The Alert mentions 'time series' but the cadences we've discussed ( say 5 per night per Lauren if I recall correctly ) don't make much of a time series. It does take a bit more reporting time to treat the 5 sets of stacked individual observations as 5 separate reports, but we should do what's best for the professional team dealing with the data. My first 5 reports were individual observations (based on stacks for snr. etc).
Gary
Hi Gary. We are still some time away from the Hubble windows of observation (January and forward). It's not critical to observe AB Aur all night continuously right now. "Snapshots" (maybe really multiple images stacked) several times during the night are plenty. Continuous time series would be -very- helpful however during the Hubble observations. Dr. Biddle is understanding of the amount of time and effort that it takes for people to do this work and so doesn't want to ask for more than necessary.
All that said, the extensive observations people are doing now are helping to understand how the photometry of the different systems compare. That will be very important to the later analysis.
-Walt
Greetings,
Perhaps it would be useful to some to also have a standard procedure for determining the mid-point-time of a set of averaged images where a few images have been filtered out. The magnitude estimate is important but the other component of the measurement is time. I've always just taken the first and last image start time and averaged those and then shift by the half the exposure time. As an alternative I suppose you could do a weighted average of the N exposure times then shift by the half exposure time. Anyone have an opinion otherwise? This is most important for fast varing objects of course.
Jim (DEY)
My readings from a single 60 second image. SNR=642 and ADU~24,000. (Max ADU is 64,000)
I use the PW CDK17 with QHY600M (binned 2x2) and Chroma Ha (3nm) filter.
I upload single images and do not combine (Stack) them.
Steve - HSTG
Please clarify…
Elizabeth
Please clarify for me exactly how I subscribe to Alert 842.
I am actively participating in the alert but am not sure I am getting alerted to each post or announcement.
thank you!
Gary
Just thought I'd add a notice about Dr. Lauren Biddle's webinar which is scheduled for this Sunday @ 2:00 p.m. Eastern Time (19:00 UTC). Dr. Biddle and Walt Cooney are planning to present their initial findings of AB Aur's variability from the first observing season, discuss some important data quality considerations, and answer any questions about relevant observing procedures and/or science goals.
You can register for the webinar here (it's free):
https://us02web.zoom.us/webinar/register/4116999884483/WN_Vr3GfhiDRMSrQpGyvrzUlA
If you are at all interested in observing AB Aur, we encourage you to attend this webinar to ensure that your contributed observations are effective in achieving the goals of the campaign, and that you get the most out of your experience as a contributor to this ambitious project.
See you on Sunday!
No Ha filter defined, unable to upload data.
Please advise.
Steve - HSTG
Steve,
I'm not a power user of VPHOT so don't know if I can help, but will try. Can you give me a little more info? I can upload images taken in HA to VPHOT without a problem. First off, I'm not sure what you mean by uploading data. Webobs is the tool for uploading data rather than VPHOT.
Clearest skies,
Walt Cooney - cwt
This is the initial campaign I've taken part in. I have been loading data into VPHOT, not Webobs. Any other direction you can provide is appreciated.
Is the data loaded into Webobs to be transformed? If so I'm not certain how to do that outside of VPHOT (maybe AstroImageJ).
Thanks
Steve Hoffman - HSTG
OK. Thanks Steve. From a nomenclature standpoint, images are uploaded into VPhot, which is then used to generate the magnitude measurements (data) that are then uploaded to the AAVSO database using webobs. The images uploaded to VPhot are deleted after a few months since storing images is spectacularly more disk intensive then storing just the photometry data derived from the images. Only the photometry data is saved by the AAVSO.
There is a trick to doing Ha photometry with VPhot. You need to change the filter keyword in the fits header of your images to R and then upload them to VPhot. That allows you to do the photometry using the R magnitudes of comp and check stars that are built into the database that VPhot is pulling from. Once you have done the reduction and generated an AAVSO report, you go into the report with a text editor like notepad and change the filter called out from R to Ha. Then you submit the edited report file with webobs.
To answer your question about transforming Ha data, no that's actually not possible. There isn't a standard catalog of Ha magnitudes for comp stars so there isn't a set of standards to try to match via transformation. Just submit as Ha magnitude for the variable using R magnitudes for comp and check.
Clearest skies,
Walt
Thank you very much.
Steve Hoffman - HSTG
I have observations in…
Hi
I have observations in Ha to upload to Vphot and process. I have no way to change the filter designation within the Fits Header from Ha to R. How is this done please?
Gary
I sent you a message on CNsSteve - HSTG
Hi Gary. Your imaging software hopefully has the ability to edit fits headers. MaxIm and Mira do. Alternatively, F4W2HDU is a bulk fits header editor. That's what I use for changing the header in lots of images all at once. It comes in very handy.
-Walt
I do have Maximdl and…
Walt
I do have Maximdl and was able to edit the headers.
Thanks for reminding me.
Gary
Although when searched there is data in Webobs with filter = Ha
I cannot see how to enter it.
Help is appreciated.
NOTE: Walt Provided the Solution.
Steve Hoffman - HSTG
Elizabeth I loaded them into VPHOT by declaring the filter to be "R". I shared them with you (WEO), I think they are good.
NOTE: Walt Provided the Solution.
Steve Hoffman - HSTG
Steve Hoffman - HSTG
You're welcome! Thanks for contributing to the campaign. If you haven't already watched the video of Dr. Biddle's presentation about the campaign, it's great. Lots of information about AB Aur and the work they are doing on it. It's on the AAVSOHQ youtube channel.
-Walt
The clouds finally parted and the FLU is almost gone.
Steve - HSTG
I am lost a bit. I try to submit individual observation, but I still don't find HA option. Would you tell me how you have solved it?
FATA
I am lost a bit. I try to submit individual observation, but I still don't find HA option. Would you tell me how you have solved it?
FATA
Did you upload your images into VPHOT?
If not how did you create the file you are trying to upload?
Steve - HSTG
Dear Steve,
till now I used to upload the observations individually , but I already realized that it won't work for HA. Instead, I created manually a file, which worked well finally.
best wishes,
FATA
I am lost a bit. I try to submit individual observation, but I still don't find HA option. Would you tell me how you have solved it?
FATA
FATA,
As you point out, you can't use the "individual observations" method to submit HA data on the webobs page. That filter is not available in the pick list. You have to use the "observations files" method instead. Then you can upload a file with your observations that says they are Ha filter and it works. That's how I do it.
Info on the format of the observation file is available at a link higher up on the webobs page. Many photometry programs have the functionality to directly output your photometry in the required AAVSO file format. Which program do you use?
-Walt
Dear Walt,
thanks for quick response. I am using astroimagej, which does not support this file format if I know it correctly. Today morning i have made a file according to the aavso instructions, and after uploading the system accepted and processed it correctly.
best wishes,
FATA
AstroImageJ supports…
Hi,
AstroImageJ supports perfectly AAVSO format. You can export exactly according to the AAVSO standards. I use it and I'm happy with that.
Guys,
I have a question about the check star 120. My FOV is 32'x32' and this star is not in the frame if I put the target right to the center.
Which check star should I use in that case? The comp star is OK, I have it!
Thanks in advance!
Nikola
thanks for…
Dear Nikola,
thanks for correcting me! I will check how it works, it seems that my knowledge is outdated.
best wishes,
Attila
I have uploaded H-alpha data directly into WebObs using the "file upload" feature. H-alpha is one of the filter choices when you do it that way.
Tom (RTH)