RR Lyrae stars in the plane

[akvivas]

I am starting a section on the detection of RR Lyrae stars in the galactic plane to be included in The Galaxy chapter. This will eventually make use of the crowding limit calculations at any point in the sky (issue #76) and metrics developed by the Variable Stars and Transients group (issue #71) @rblum5 @willclarkson @lmwalkowicz @StephenRidgway

[bethwillman]

Will evaluating the detectability of periodic variables in crowded regions necessarily need to make use of the crowding calculations? I was thinking that a combination of a map of interstellar extinction, a set of RRL templates (plus ranges of periods and amplitudes), and the 5 sigma difference image limit in delta magnitude is what could be used for calculating this metric.

On Fri, Aug 21, 2015 at 3:44 PM, Kathy notifications@github.com wrote:

I am starting a section on the detection of RR Lyrae stars in the galactic plane to be included in The Galaxy chapter. This will eventually make use of the crowding limit calculations at any point in the sky (issue #76 https://github.com/LSSTScienceCollaborations/ObservingStrategy/issues/76) and metrics developed by the Variable Stars and Transients group (issue

71

https://github.com/LSSTScienceCollaborations/ObservingStrategy/issues/71) @rblum5 https://github.com/rblum5 @willclarkson https://github.com/willclarkson @lmwalkowicz https://github.com/lmwalkowicz @StephenRidgway https://github.com/StephenRidgway

— Reply to this email directly or view it on GitHub https://github.com/LSSTScienceCollaborations/ObservingStrategy/issues/88 .

Beth Willman AURA/LSST Deputy Director Associate Astronomer, Steward Observatory 933 North Cherry Avenue Tucson, Arizona 85721 520-318-8473

[akvivas]

The crowding limit will help to evaluate what are the faintest RR Lyrae stars we can detect (in combination of course of a map of interstellar extinction). This would answer how far can we detect RR Lyrae stars and how well can we sample the disk (can we detect distant stars on the other side of the disk?) @bethwillman

[akvivas]

ok... got your point now, Beth. Differential imaging will be the way to go in crowded regions. Excellent!

[willclarkson]

@akvivas - I think this is an important point, that the crowding limit is different for different kinds of investigation. Hopefully the metrics will be sophisticated enough to deal with this.

e.g. pseudocode might be something like: if (ThisMetric is Variability): deepLimit = CrowdingLimit(UsingDIfferenceImaging = True) else: deepLimit = CrowdingLimit(UsingDifferenceImaging = False)

Dr. Will Clarkson Assistant Professor of Physics and Astronomy University of Michigan-Dearborn Students: please put your course code in the title of emails to me (ASTR421, PHYS150 or PHYS126).

On Fri, Aug 21, 2015 at 4:05 PM, Kathy notifications@github.com wrote:

ok... got your point now, Beth. Differential imaging will be the way to go in crowded regions. Excellent!

— Reply to this email directly or view it on GitHub https://github.com/LSSTScienceCollaborations/ObservingStrategy/issues/88#issuecomment-133584151 .

[knutago]

So one way in which the confusion limit enters is for measuring the zero point of the brightness of the variable stars. Difference imaging is great for measuring Poisson-limited changes in source brightness, but for measuring distances with RR Lyrae, you also need the mean apparent luminosity. And a crowded field will have extra Poisson noise from neighboring sources...

On Aug 21, 2015, at 4:10 PM, Will Clarkson notifications@github.com wrote:

@akvivas - I think this is an important point, that the crowding limit is different for different kinds of investigation. Hopefully the metrics will be sophisticated enough to deal with this.

e.g. pseudocode might be something like: if (ThisMetric is Variability): deepLimit = CrowdingLimit(UsingDIfferenceImaging = True) else: deepLimit = CrowdingLimit(UsingDifferenceImaging = False)

Dr. Will Clarkson Assistant Professor of Physics and Astronomy University of Michigan-Dearborn Students: please put your course code in the title of emails to me (ASTR421, PHYS150 or PHYS126).

On Fri, Aug 21, 2015 at 4:05 PM, Kathy notifications@github.com wrote:

ok... got your point now, Beth. Differential imaging will be the way to go in crowded regions. Excellent!

— Reply to this email directly or view it on GitHub https://github.com/LSSTScienceCollaborations/ObservingStrategy/issues/88#issuecomment-133584151 .

— Reply to this email directly or view it on GitHub https://github.com/LSSTScienceCollaborations/ObservingStrategy/issues/88#issuecomment-133585703.

[drphilmarshall]

A quick search of the PDF shows that RR Lyrae are currently only mentioned in the Special Surveys chapter. Are you planning on checking in some Galaxy text, @akvivas?

[akvivas]

Closing this one since it is not within the current structure. May be re-opened later if needed.