1. Crowded Field Photometry Stars, Milky Way, Local Volume
LSST 2016
John Gizis
University of Delaware

2. SMLV Crowded Fields… Executive Summary = Questions
SMWLV is interested in both photometry and astrometry in crowded fields, meaning PSF fitting of multiple overlapping stars.
What is the baseline plan for crowded fields?
What does the Project need from SMWLV?

3. What is the baseline plan?
What will DM do in terms of very crowded fields?
Is the community responsible for running DAOPhot or similar? What is Level-3?
Computational demands. Can this fit within planned Level-3 resources? Is this left to users? Where does process happen?
Can user run DAOPhot using LSST resources on Area X with specified parameters?
Getting images to individual investigators may be bottleneck.
Will science be restricted to large institutions?

4. What are the plans for testing?
SMASH etc. are valuable datasets
Simulations with artificial stars.
What is schedule?
What will Project do?
What can SMWLV do?
SMWLV/DAWG plans to look at Gaia crowded field astrometry.
It is not trivial for ordinary user to get DM running. Would need support if SMWLV is reponsible for tests.

5. Does Project need specifications?
Assuming DM is going to run some sort of DM pipeline on crowded fields…
Does DM need SMWLV to set requirements or goals? Example: Recovery rate.
Suggest datasets?
Analyze tests?

6. DAOPhot/DoPhot Industry standard.
Minimum: Validate DM Catalog (Level 3 Product?)
Who is responsible?
What resources are available?
Question: Are we better off just using this software?
Scaling [A. Saha]: DoPhot, Baade’s Window, r<24, avg sep 1.5”, 0.8” seeingone hour/million objects on desktop
See Koposov et al. (2015) as possible model of community analysis. Sextractor, PSF fitting…

7. Difference Imaging We assume this is going to happen…
Are there issues with difference imaging in crowded fields?
What is validation plan?
Note: Colin Slater, etc. comments in DM session this morning.

8. More thoughts…
LSST Alert Production: matching to a reference catalog, determining an accurate WCS, a photometric zero- point and an accurate PSF
LSST needs to produce good image stacks even in crowded fields.
Can we get a Project commitment to this?
This would enable a community DAOPhot-like effort.
[Thanks Clarkson/Nidever]

9. Identifying a team
Can we find people to take leadership roles on these issues in Project or SMWLV? Is there a “champion” of crowded field photometry?
Communication between Project and SMWLV (and Transients…)
What structures can we have?
Online discussion, videoconferences, etc.
Is there need for a document?