Affiliation
American Association of Variable Star Observers (AAVSO)
Mon, 05/19/2014 - 04:29
Ok, so I'm not sure where to post this, so I thought I would post under general for now...
I created an observing list with the help of the Observation Planning tool, and have found that many of the suggested stars that I encountered either do not have sequences or their sequences are inadequate for the magnitude range of the target. Is there a way to request that a new sequence be created? I know there is an AAVSO sequencing team, but don't know how/where to make this request.
Thanks,
Brian (PRV)
[quote=potterrb]Ok, so I'm not sure where to post this, so I thought I would post under general for now... I created an observing list with the help of the Observation Planning tool, and have found that many of the suggested stars that I encountered either do not have sequences or their sequences are inadequate for the magnitude range of the target. Is there a way to request that a new sequence be created? I know there is an AAVSO sequencing team, but don't know how/where to make this request. Thanks, Brian (PRV)[/quote]
OK, if the sequence is inadequate or needs reviewing or extending, go to
http://www.aavso.org/chet
The Chart Error Team is made up of a number of amazing people. I can not sing their praises too highly. They have been a BIG help to me and many others.
If there is no sequence, then you need to go to
http://www.aavso.org/request-comparison-stars-variable-star-charts
and read the instructions very carefully.
Good luck with your observing
Stephen [HSP]
New Zealand
Thanks Stephen, your response is exactly what I needed!
Regards,
Brian
While I am not suggesting that this was an issue for Brian it has been my expierence that even after we modified the underlying language that explains the limitations, conditions and purposes of this useful tool (Observation Planner) that far to many of the folks that discover it do not take the time to read about those limitations, conditions and purposes....
http://www.aavso.org/observation-planner-tool
Therefore, Please, Please, Please carefully read all the language below the data entry form to get a better understanding of what the tool can and can not do before you first attempt to use it.
Tim Crawford, CTX
Mentoring Team
Hi Tim,
Thanks for your reminder to read the disclaimer on the observation planner, and for artfully avoiding directly suggesting that I did not read it. :-)
I find the planner useful, disclaimer and all, for identifying stars that are worthwhile measuring. And the disclaimer is correct...you essentially need to "validate" each of the suggested stars before adding them to your observing list. You must determine that the star is of interest, has a reasonable number of people measuring it, etc.
The two situations I encountered are as follows. First, S Sco has a sequence nearby, but the sequence did not appear to go deep enough. I did consult with the sequence team, and they have added additional stars although they believe a 151 comp was already available and the dimmest I saw was 140. Regardless, they added additional 14th mag stars and I am in business.
The more interesting situation is for HO Lyr, which lies between two different sequences. To the northeast there seems to be a sequence for PF Lyr, and to the southwest one for EQ Lyr. In either case my FOV, if centered on HO Lyr, does not encompass either set of comps. If I center on either set of comps, HO Lyr is not in the FOV. So if I want HO Lyr and a sequence in the same FOV, I either need to center the FOV on coordinates midpoint between HO Lyr and a sequence so that both are in the FOV, or I need to request a sequence be created near HO Lyr. I assume this situation occurs elsewhere but this is the primary reason for my request for assistance.
Any thoughts?
Thanks -- Brian
Are we not able to delete comments?
Hi Brian,
If you look at the 4000 day light curve for HO Lyr, you see that there is a discrepancy between the CCD observers and the visual observers - the visual observations stop around V=13.5, while the CCD observers go to V=15. Looking at the DSS chart, there is a close V=13-14 companion to the southeast, and most likely either the visual observers are measuring them both as a blend, or reporting the companion when the Mira is faint. Be very careful with this star. My recommendation on all such objects is to avoid them - there are plenty of other Miras around, and nothing unusual about this one that deserves a complication.
As for S Sco, it is about 10arcmin east of M80 (NGC 6093), which always makes it interesting to me! I'm surprised there aren't more observations of it in the database. You may not have set your minimum magnitude faint enough if you didn't see the 151 comparison star, but asking the chart team to fill in the faint range was a good idea.
Arne
As Arne pointed out, HO Lyr has a close companion. It is 9" away and has V= 14.1.
This is a potential source of problems: when the mira gets faint it might be misidentified and when it is bright, the two might be blended and measured together.
I have added a VSP note so new observers are warned.
This star deserves a place in the list I published here:
http://www.aavso.org/variable-stars-companions
I will update the spreadsheet soon because there are (unfortunately) several more new examples of stars with close companions. I will post an update.
In the meantime, it is good to remember the HQ policy on this regard:
HQ POLICY for stars with companions:
HQ strongly suggests that, if you can only report a blended magnitude on some target, you delete this target from your observing program. Focus on the stars that can be cleanly observed with your equipment. Also, be careful with the variable identification when it is at minimum. Maybe you can cleanly measure the stars if you identified them by hand, but if the variable gets so faint that it becomes invisible, you (or your software) might confuse it with the companion. Be sure you use a chart that shows the field in detail that is suitable for the variable’s brightness – you need more detail when the star is faint than when it is bright. Also, do not push your observing equipment further than it can go, a problem easy to happen for visual observers with smaller telescopes.
If you have already submitted data for any of these objects to the AID, double-check to see if you reported the correct star or that your results are not blended. If you did observe the wrong object, please delete the observations. If your observations are blended, you can add a comment in your report mentioning that fact (something like "The 14th mag companion to the NE is included in the aperture").
Hi Arne,
It is good to hear of stars that are interesting in some way, especially when trying to decide what Miras to observe. Based on your comments about S Sco, I will definitely keep it on my list.
Do you have other Miras that you are especially fond of and that would be worthy of adding to my observing list? I observe visually with binoculars (I have a pretty solid binocular program setup) and a 10" reflector from here in the light-polluted skies of SE Michigan (42deg N), but also have begun to use iTelescope.net for CCD observations as well.
Thanks -- Brian
Brian,
One of the better sources and one of the more important ones as it will lead you to a number of legacy Mira's:
https://sites.google.com/site/aavsolpvsection/Home
By the way, when visually observing Mira's it is a good idea to be aware of the Purkinje effect:
THE PURKINJE (pooR-keen’yA) EFFECT ON RED STARS
"The Purkinje phenomenon makes red stars (i.e. Mira’s) seem brighter the longer you stare at them due to the response of the retina to red light. This makes estimating red stars even more difficult than it already is.
When observing these stars it is recommended that you use the quickglance or out-of-focus method. The former involves quickly glancing between the comp stars and the variable. The latter involves slightly defocusing your telescope and making an estimate of the defocused image."
My email address: tcarchcape@yahoo.com
If you send me an email I will email you a pdf document: Variable Star Target Opportunities......that should be of general interest to you. It does not specify specific stars but will direct you to a number of various pgms and sites where individual targets are listed. I will also enclose a short pdf on why Sideral Time is Our Friend (the first document has a brief remark on this).
I appreciate your enthusiasm; keep up the interest and do not be afraid ever to ask for help.
Just remember that there is no such thing as a dumb question.
Ad Astra,
Tim Crawford, CTX, Mentoring Team
[quote=CTX]
Brian,
One of the better sources and one of the more important ones as it will lead you to a number of legacy Mira's:
https://sites.google.com/site/aavsolpvsection/Home
By the way, when visually observing Mira's it is a good idea to be aware of the Purkinje effect:
THE PURKINJE (pooR-keen’yA) EFFECT ON RED STARS
"The Purkinje phenomenon makes red stars (i.e. Mira’s) seem brighter the longer you stare at them due to the response of the retina to red light. This makes estimating red stars even more difficult than it already is.
When observing these stars it is recommended that you use the quickglance or out-of-focus method. The former involves quickly glancing between the comp stars and the variable. The latter involves slightly defocusing your telescope and making an estimate of the defocused image."
My email address: tcarchcape@yahoo.com
If you send me an email I will email you a pdf document: Variable Star Target Opportunities......that should be of general interest to you. It does not specify specific stars but will direct you to a number of various pgms and sites where individual targets are listed. I will also enclose a short pdf on why Sideral Time is Our Friend (the first document has a brief remark on this).
I appreciate your enthusiasm; keep up the interest and do not be afraid ever to ask for help.
Just remember that there is no such thing as a dumb question.
Ad Astra,
Tim Crawford, CTX, Mentoring Team
[/quote]
[quote=CTX]
By the way, when visually observing Mira's it is a good idea to be aware of the Purkinje effect:
THE PURKINJE (pooR-keen’yA) EFFECT ON RED STARS
"The Purkinje phenomenon makes red stars (i.e. Mira’s) seem brighter the longer you stare at them due to the response of the retina to red light. This makes estimating red stars even more difficult than it already is.
When observing these stars it is recommended that you use the quickglance or out-of-focus method. The former involves quickly glancing between the comp stars and the variable. The latter involves slightly defocusing your telescope and making an estimate of the defocused image."
[/quote]
Never knew how to pronouce that word. Thanks for the info.
Rich Tyson
For inadequate sequences, go to http://www.aavso.org/chet. For new sequences, either go to that same site or see http://www.aavso.org/request-comparison-stars-variable-star-charts. We create or update sequences as quickly as possible!