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Help with VSP

evan_aavso's picture
evan_aavso
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Joined: 2011-02-12

Hello


I am trying to compile a short list of targets to observe that are known to be variable stars but currently have no observations submitted on VSX. When I try to look up field charts for a specific star, sometimes there are no known targets within the given field perimeters. The only run around I have found is raising the scale to "A" which gives me a return of around 100 stars to choose from which sounds like too much for what's required. To sum it all up, how can I get a quality list of stars to use as comparison / check stars for a target star that has no field chart worthy of analyzing?

 

Thanks

Evan

Understudied Targets
CTX's picture
CTX
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Joined: 2010-07-08

Evan,

I suspect from your mention of an A scale chart that you might possibly be looking at Bright targets as a Visual observer.  If this is so, then you might have two other options. 1) the VSP allows you to specify a magnitude limit under the Miscellaneous options (about 1/2 way down the option list). 2) Did you try specifying a Binocular Chart?  This is an option near the bottom of the VSP option list and it may or may not be a suitable option for your target.

If neither of these two suggestions resolve your problem then you might consider one of the following:

Observers can make a request for a sequence for field of views for which no sequence exists at all:

http://www.aavso.org/request-comparison-stars-variable-star-charts

Observers can also make a request for additions or extensions of existing field of views where some sequence data exists:

http://www.aavso.org/chet

Observers should carefully read the instructions in both cases before making a request.

I would also like to make some general remarks about understudied targets that might be of benefit to you and other observers.

Understudied Targets

I suspect that some observers may be presuming that because a target is in the VSX and because it might show only a few or no observations that it is automatically a worthy target.

Sometimes this may be true and other times there is a good reason that a specific target is understudied. 

A portion of those understudied targets will turn out to be multiple systems, i.e. close doubles, which makes photometry challenging. Many of them are Miras or other LPV’s which require years, sometimes, of continued study to generate useful information and a few random observations therefore may not be to significant.  Sometimes there is simply no available suitable sequence; either because one has not been created, sequence data may not be available or that portion of the sky may simply not contain any stars for the purpose (tends to be more of an issue with some of the brighter targets).

Speaking of long period variables, the AAVSO maintains a web page with links to specific targets in need of observations that observers should at least be aware of:

http://www.aavso.org/program-stars-need-observation

I would like to encourage those who data mine for understudied/under observed targets to check the variable type and then to do some research regarding that type of target before concluding that it is a worthwhile target for them to observe.

http://www.aavso.org/vsx/help/VariableStarTypeDesignationsInVSX.pdf

The above link will take you to a pdf of descriptions of the various types of targets listed in the VSX.

Also, a great resource, in addition to a search of the AAVSO site is the SAO/NASA document inquiry RE specific targets or types.  You can search by specific target names and or types and see what might be available.

http://adsabs.harvard.edu/abstract_service.html

Having said this, it is not my intent to suggest which targets or worthy of observing and which are not, as I am not really qualified to make any such judgments.  It has been the history of our fine organization to not interfere with the target choices of observers.  Such choices should be left to the observer and I fully support this practice.  All I am suggesting is that with the understudied targets that the observer make an informed choice, whatever it might be.

I do sympathize with all observers as sometimes it is difficult to know what should be observed and we all want to feel like we are making important contributions (we are) and/or even maybe making a significant discovery along the way.

FYI, I do have a 5 page pdf document (Variable Star Target opportunities For all levels of Experience) that I put together to aid those looking for target opportunities.  I am happy to share this with anyone that makes a request (tcarchcape@yahoo.com).

 Ad Astra

Tim Crawford, CTX

Understudied targets
MDAV's picture
MDAV
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Joined: 2010-07-23

Evan:

The only thing I can add to Tim's recommendations is that if you pick one of these that you stay with it and make observations at regular intervals.

An increasing problem is the reduction in the number of visual observers as people switch to instrumental photometry. One result is that stars which previously had coverage lack it now.

There are many stars where the only reason we have a light curve is because a dedicated observer-somtimes a single one- persevered long enough to get the data to make one.

I appreciate the responses
evan_aavso's picture
evan_aavso
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Joined: 2011-02-12

I appreciate the responses from the both of you, very informative. For me I have a lot more fun observing stars that are either understudied or have a few observations but not enough to compile good quality data. The only problem I have found with understudied targets is either no sequence stars, or like what Tim pointed out earlier some of these stars have close stars in the proximity making photometry difficult. Anyways thanks again for the reply.

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484