gmosfc

Handy GMOS finding chart generator.

gmosfc generates finding charts for Gemini-GMOS spectroscopy, using either archival sky survey images, or by generating synthetic images from GAIA DR2 photometry.

Installing

The following dependencies are required:

• Python 3.7.1 or later
• Numpy 1.11 or later
• Matplotlib 3.1.1 or later
• Astropy 4.0 or later
• Astroquery 0.4 or later
• APLpy 2.0.2 or later
• photutils 0.7.2 or later

You can install APLpy and all its dependencies with:

python3 -m pip install gmosfc

Examples

Once installed, you can begin generating quick finding charts for a variety of GMOS modes.

1. GMOS two target acqusition, using synthetic GAIA DR2 images

Create a GMOS finding chart for a two target acqusition using synthetic GAIA DR2 images. You must enter the target name, and User 1 and User 2 coordinates in the astropy.SkyCoord format. The desired position angle, and the Base coordinates are calculated, and saved to the log. Optional arguements include Program ID, slitwidth (default of 1 arcsec), position of the scalebar, and SkyCoord options unit, frame, and epoch. Do not use the GAIA synthetic images if your target is a galaxy.

import gmosfc as gfc
gfc.gmos_twotarget_gaiasyn("Pismis24-17+Pismis24-16", 261.186378, -34.200760, 261.185225, -34.199680, slitwidth=2, pnum='GS-2020A-Q-403', markersize=25, markersizecentral=0)     
...
Finding chart saved as Pismis24-17+Pismis24-16_fc.jpg
Cleaning up

The image is saved in the same directory, as the Pismis24-17+Pismis24-16_fc.jpg

The utility of the GAIA synthetic images can be seen when you compare to the DSS finding chart created using the following command (see the zoomed in comparison)

gfc.gmos_twotarget("Pismis24-17+Pismis24-16", 261.186378, -34.200760, 261.185225, -34.199680, slitwidth=2, pnum='GS-2020A-Q-403', markersize=15, markersizecentral=0)

Looking at the zoomed in comparison of the GAIA synthetic and DSS finding charts, the image quality is apparent, as is the usefullness for the observer.

2. GMOS blind offset acqusition, using DSS images

Creating a GMOS finding chart for a blind offset acqusition using DSS images. You must enter the target name, Base and User 1 coordinates. Additional arguements include the sky survey (deafults to DSS), which can be chosen from https://astroquery.readthedocs.io/en/latest/skyview/skyview.html

gfc.gmos_blindoffset('SDSSQuasar', '20h54m0.8016s', '-00d05m29.04s', '20h54m07.678s', '-00d05m31.92s')
...
Finding chart saved as SDSSQuasar_fc.jpg    

We see now that the finding chart, and also that the default choice of scalebar position does not cover the compass.

3. GMOS long slit target with position angle

A bright single target, with a desired position angle is entered as

gfc.gmos_longslit('HD99', HD99', 001.492803, +44.739380, pa=123.4)

With the resulting finding chart

For further information, please see documentation.

Citing

If you have found this snippet useful, please give us a star.

Contact

If you have issues with the code, please contact the author at vkalari@gemini.edu