Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 12/07/2021 - 06:45
AAVSO Alert Notice 761 announces an observing campaign on the triple-component eclipsing system b Per, which has an eclipse in December 2021. Please see the notice for details and observing instructions.
There are threads for this campaign under the following forums:
- Campaigns and Observation Reports: https://www.aavso.org/b-per-dec-2021-eclipse
- Eclipsing Binaries: https://www.aavso.org/b-per-dec-2021-eclipse-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
My best option for collecting data on this eclipse is with the TG channel from an Ha-modified DSLR. Would this be of value? I know that the modification changes the spectral response so I wanted to check first.
Richard
By all means yes! There is a paragraph in the alert notice about DSLR's and photometry and references for further guidelines. I believe most of the observers have made their observations with DSLR's - and those data have been very good!
Thanks for joining the forum.
Good observing!
Don Collins (CDK)
That is exactly what I am doing to support this project. I found that my Canon dslr was better suited than my astronomy camera because it is less sensitive. Even so, I am using a 5 second exposure at ISO400 in my modified Canon 600D with its 300mm zoom lens. It rides piggy-back on my 8" SCT. Now let's hope for clear skies as we approach the eclipse on December 23.
Rick
Welcome to the b Persei forum. Here I and observers can post some developments and progress of the eclipse. Especially valuable is when observers first detect dips in the light curve as the third star begins to occult one of the inner pair. In January of 2020, day 1866 on the January 2020 eclipse (Figure 2 of the alert notice 761) several observers detected the early grazing eclipse about a day before the mid-eclipse. Very valuable observations! It will help to pin the sizes and positions of the three stars which we cannot resolve in the sky.
Good observing, everybody!
Don Collins (CDK)
I am hoping to to help…
Hi,
I am hoping to to help with this project, although I don't have much experience in determining light curves.I have read about using DSLR cameras for plotting light curves, but I have not done any yet. I have an 8" F5 newt and a Canon 60D (not modified)
I have done a fair amount of general imaging and I understand about de-focusing and not oversaturating the sensor in order to keep everything linear. but I just need to practice on getting usable images.
Hope I can help...
Thanks
Robi
We are glad that you…
Robi,
We are glad that you wish to join the campaign to observe b Persei with your DSLR and telescope. Be sure to use raw mode in imaging. If you haven't gotten an observer code from AAVSO, be sure to get that from the AAVSO website. It's free! Would you mind telling us where you will observe from. We hope to have a good geographical distribution of observers. Also try to get images as soon as possible. Also you will need some photometry software. Muniwin is a free program that is good. For light curves we take successive images for as long as possible and run the photometry on many images at once the next day.
Welcome!
Don (CDK)
I am a member of…
Hi Don,
I am a member of AAVSO and have an observer code. I am in Santa Clarita, CA. I will take a look at Muniwin, thanks for the recommendation .
I'll get set up and start taking images soon . I assume I will need to take darks and flats also?
I have a QHY5 mono camera that I usually use for guiding, would this be better suited for this project than a DSLR?
Thanks
Robi
Hi Robi, I am unfamiliar with with the QHY5 camera. My guess that it is much more sensitive than a DSLR. b Persei is so bright that well-focused images saturate very easily. I placed the heading in the subject line hoping some other observers who are familiar will respond.
Good observing!
Don
Robi,
I am not familiar with the QHY5 camera but if you are going to use it I would recommend using it with a tricolor green or photometric V filter. Whichever camera you use, I think the big factor needs to be the field of view you will have with the QHY camera or DSLR camera. You will need a field of view large enough to include the target,comparison, and check star. b Per is separated from the check star by a little over 37 mins. The comparison star is in between the two. So you will need a FOV greater than 37 arc mins. You may have more options with your DSLR and telescope or camera lens, then extract the 2 green channels in your DSLR image. And yes, calibration is recommended for either camera.
Barbara
Last night I took exposures at different times to see what works best, however when I process the images in Muniwin they report B per as around mag 12, with the difference between B per and HIP 20156 at around 0.5.
I must be doing something wrong, but I'm not sure what. The best images seem to be 11 seconds at ISO 200. I don't think I am saturating the image.
BTW, my canon 60d with my 8" f/5 newt gives me a FOV of 76 x 51 arc-min with a 1000mm FL, so I am able to get HIP 20370 in view also.
I appreciate any advice.
Thanks
Robi
Robi, I'm not sure not having worked Muniwin for many years. Many programs report magnitude as "Instrumental magnitude" which is -2.5 * log(flux ratio) without the standard constant. The apparent magnitude is then the difference between the instrumental magnitudes of the two stars. You will also need to take many images (about 10 at 11 sec) and average the results due to scintillations with short images. Good Luck!
CDK
Robi,
You said that you “don’t think I’m saturating the image”. This is something that you need to make sure of because if your target is saturated then your images are useless. Not familiar with Muniwin but most software packages should be able to measure the max ADU of your star. If you are saturating then going down to ISO 100 may help and/or shorter exposures.
Barbara
I am also using a Canon DSLR to observe B PER. My modified Canon 600D with its 300mm zoom lens (F 5.6) has a field of view of about 5 degrees by 3 degrees. I am using 5 second exposures at ISO400. I then process the images using ASTAP, which does calibration, plate-solving, and photometry, all within that one software package (freeware). Once you learn how to use the software and which settings are important, it is easy and quick to generate an AAVSO compatible report file from a batch of raw .CR2 images. You then just upload the report file. It even generates a time-series 'light curve' for that batch of images.
Plate-solving is the key to making this work. I gave up long ago trying to figure out which little dot was which star on a finder map from the AAVSO website. ASTAP does all of that for you, and labels the comparison stars using the AAVSO database.
Rick
Rick,
I have ASTAP for plate solving with APT (Astro Photograpy Tool) which I use to control my Canon and my CGEM from my laptop. I didn't know it could do photometry. I will have to look into that. I actually center on HIP 20156 to make sure I get the check star in my FOV.
How do you measure the ADU in ASTAP to make sure you aren't saturating the image?
Robi
I too use ASTAP with APT to control my scope and cameras. With my large field of view (270 x 180 arcminutes), I just center on the target with no worry about enough comp stars being visible. There are a couple of ways to check for saturation, both in APT and in ASTAP. In APT, I use the "pixel tool" and the "focus tool" to give me an idea of the saturation state. And then in ASTAP's viewer window, you can hover over the star with your mouse and see various values for that star in the bottom line of information. Don't be mislead by the values called "RGB Screen" ... that's not the image ADUs, but the displayed intensity. I have created a written tutorial for using ASTAP for photometry, based on my own experience and the ASTAP homepage. Send me private email at hrickdiz@gmail.com and I will send it to you.
I have…
Hello Don,
I have participated in previous campaigns of eclipses of b per. This time the weather has not been good and there have been few days with the opportunity to make observations. I have submitted just now the observations of December 13, 14, 15 and 16, several hours per night, in total 197 observations. I hope they can be useful even if they are far from the eclipse day.
Regards,
Javier
Hi I'll be using my LOCAMS system here in southeastern Arizona USA to collect (hopefully) calibrated photometry of b Per every 10 seconds during the campaign. This station is part of the Global Meteor Network, but obviously it can be used for sooooo much more. This is a new installation so I'm curious to see how well it performs.
Cheers and Happy Eclipse!
Matt Cheselka (GMN stations USL[00X][00Y][00Z][010][011][012])
AAVSO Observer Code: CMAH
Got what looks like good data here on the first day of the campaign. Here's a small portion of an image taken 2021.12.16 at 10:01:05 UTC.
b Per is the upper right star. From today, I've got about 4200 images with a cadence of 10 seconds, and that's about what I'll have every clear night. The pixel scale here is about 4 arc *minutes* per pixel -- it's an all-sky camera. It's suppose to be clear again here tonight, but maybe cloudy for a few days after that....
Cheers,
MC
I don't think that the forum can take attachments such as images. It is best that you post it on a site that you own and include a link to it. I'm anxious to see the all sky images.
CDK
I don't think that the forum can take attachments such as images. It is best that you post it on a site that you own and include a link to it. I'm anxious to see the all sky images.
CDK
I've got data, but not very much due to a very bright moon and clouds. I'm going to collect all of the data now and process it after the campaign is over. It's very exciting to hear that brightness changes have been noticed these past few hours.
Cheers and thanks for the updates!!!!
Matt
I have some data, but unfortunately it was cloudy during most of the campaign. Of what I have, I'll do my planned differential photometry and post the results asap.
Cheers,
MC
It's good to see the data coming in while preparing to observe the eclipse of b Persei. I expect the eclipse to begin late in the Julian date 2459570 which is Jan 22 midday for Europe and N. America if my arithmetic is correct. We need as good coverage as possible the next 5 days!
Clear skies!
Don (CDK)
b Per is (18:18 UT, Dec, 22) 0.3 mag below the minimum value of the last days! Maybe a first sign of eclipe.
Unfortunately, more and more clouds are appearing....
Hans-Georg Purucker (PHG)
I have just submitted my latest observations to WebObs.
I use a normal tripod with Sony alpha 6300 camera and 85 mm lens. In one session I take always 27 pictures of 8 sec at f 8 (without tracking).
After flat correction the pictures are split in R, G and B channels (for Sony alpha no dark correction is necessary). The 27 (fits) images in G are stacked with median function (Fitswork). Simple differential photometry (b Per vs "55" comp) delivers one single observation.
Hans-G. Purucker (PHG)
I think the b Per eclipse has started just before 19 UT.
I am taking 30 sec RAWs using DSLR with APO 102mm F/7 on EQ3-2 mount with drive. Simple differential photometry (b Per vs "55" comp) on RAWs using IRIS shows about 4,70 - 4.72 mag for b Persei. I get it on all measured RAWS after 19 UT. The weather is rather hazy with cirrus.
All,
I'm on the target since 17h00 UT, using about the same scope that Rybi : 102APO f6 + DSLR raw and Iris for TriG photometry.
The LC seems to show a "break" near 18h06 UT. (JD2459571.25439812).
Now, high altitude clouds are coming more and more. It could be over very soon, from here.
Cheers.
Christophe
Looking at the data that have been posted on the AAVSO light curve generater it looks like the eclipse had started last night. It is predicted to be quite deep tonight!!!!!
"tonight" means 2021 - Dec. 21 UT
I don't have access to a live telescope.
All eyes up!
CDK
Clouds kept me from getting much data earlier in the week, so I haven't been able to check out my new setup (100mm telephoto, V filter, QHY294M), but I'm fairly confident that b Per is currently at V ~ 4.94 (0h UT 12/23). It looks like the eclipse is well underway. Hopefully, some western Europeans are still observing so we get good coverage of the start of the eclipse.
Shawn (DKS)
I started collecting data at 00 UT 12/23 and got a TG mag similar to Shawn at 4.959. My previous data was collected on 12/12 with a mag around 4.6.
Barbara(HBB)
All,
Under a clear and blue sky, I could get some data showing that b Per is near 4.94-4.95 in my system,
JD 2459572.20083877 to 2459572.21010817 (UT 16:47 to 17:01 dec 23).
The clouds are coming soon. Maybe a couple of hours of clear sky before going under the cap. Next days will be clouded and or rainy.
Cheers,
Christophe
Merry Christmas to everyone who have been observing the eclipse and those who have observed the out-of-eclipse even though many have been clouded out during eclipse! The final emergence of a final dip in brightness is expected today around noon UT. I hope we caught some ingress into the final partial dip expected from N. American observers. Europeans may catch the egress out of the final partial dip tonight. It is also important to continue close long-term observing all night tonight and all night on Dec. 25-26. The robotic telescopes don't take a holiday so they have been a big help.
I also request that all observers obtain a substantial run after the eclipse so that we can calibrate everyone's observations to a standard curve.
Best wishes for the holidays!
Don
(CDK)
Greetings,
I took a series of V (Astrodon filter) of b Per last night, 2021 Dec 23-24. I decided not to stack, smooth, or otherwise adjust the measurements. So what I uploaded are 0.25s images with about 10s of CCD readout dead time between. DNs were around 30K near the middle of the dynamic range of the CCD. Atmospheric flicker rate was visually very fast last night.
Second night 2021 Dec 26-27th. I formed single means for V and B to fill a hole in the LC--at the time of upload. Very poor weather conditions, variable clouds so the scatter is very large for individual images, but the means may be usable.
Jim DeYoung (DEY)
The eclipse is now well completed. Excellent coverage by those observers who had good weather! We have a good ingress to the deep eclipse and the steep egress out of the main eclipse. I hope someone comes through with observations from the "white-out" times of Europe and N. America where partial dips were expected. I will proceed to slowly compile the data, smooth the data from rapid atmospheric scintillations and short exposures, and adjust the zero levels so the out of eclipse observations match. The out of eclipse observations are extremely important, so please obtain at least a 4 hr run for at least one night of out-of-eclipse data using the same protocol as the in-eclipse data. If weather prevented eclipse data, all the out-of-eclipse data are important and useful for characterizing this star system.
Again many thanks for another successful campaign! I will publish processed light curves on the forum, so please stay tuned. The next eclipse is a secondary eclipse in September, 2022. I believe b Persei will not be high until after midnight.
Don Collins (CDK)
I have uploaded measurements of the 28th, 29th, 30th and 31st, in total 79 observations.
Regards,
Javier
After all the storms here in SoCal, I finally had some (mostly) clear skies last night. I did a three hour run at 1 min cadence and got some good follow up data. I wish I had gotten some images of the actual eclipse.
I would like to thank Rick for helping me figure out how to use ASTAP to reduce the data and get a good light curve.
Var star, median: 4.549, σ: 0.01779
Check star, median: 5.452, σ: 0.01779
Now I'm going to go practice on some other variables so I'm ready for B Per next time
Robi
Hello observers,
I have processed the observations of b Persei of the December 2021 primary eclipse. You may see the finished curve at the following link: D Collins b Persei Results. These results have time-binned observations from an observer if there were excessive scatter due to short exposures needed for CCD detectors. The observers results were also offset by an additive or subtractive constant so that the out-of-eclipse observations were well fitted to the out-of-eclipse ellipsoidal curve. I did not include observations that did not span much time or did not occur during the eclipse. At a later time I will assemble a period-folded out-of-eclipse light curve which will include the "snapshot" observations. I will also assemble and display the predicted light curve that was displayed in the alert notice so we can compare the prediction with the data. Thank you observers for the good data!
D. Collins (CDK)