2025 Spring Lab Notebook

2.19

Working on paper figures. Concern that the plots we made for the 1000 image sequence are dominated by drift from the source separation in a given pair of beams. Some example plots of this are below.

Open

Open

The red line is temperature and the blue is source separation, for different pairs of beams. We want to compute a running mean for this data and subtract it for all source separation values before taking our standard deviation.

The computed running mean with a window of 20 points is shown in the figure above. We now take this mean and subtract from the y source separation values for beam pair 0.

The new plot looks relatively similar to the previous 1000 image plot (shown below); the x pairs are much flatter

Old plot:

Elana also had the idea to compare this with the ellipticity of our first batch of on-sky data points, so we can make a stronger argument that this dome seeing is directional.

Procedure

• Galsim, make a box around each star to find the PSF

• Rotate the ellipticity back around into the correct x,y frame

  • Coordinate transformation is the same as before to figure out the major/minor axes

2.20

Elana sent me a source that breaks down ellipticity and what its components mean.

https://watermark.silverchair.com/stx3366.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9C[…]JyM5hOzNvorILTCImN4VdB2pg5ud_lnCDPPzZnZcnnOdve1B0SQ42ENw

I have a code block that calculates the ellipticity components e1 and e2 given the approximate coordinates of a star. I calculate ellipticity and its components e1 and e2 (stretching along x/y and y=x/y=-x). Once I calculate the components, the ellipse's major axis is at an angle a = 1/2 arctan(e2/e1) from the positive x-axis, so then I can calculate what the rotation of the focal plane was for this image, and from that back out this angle in that reference frame.

2.21

Just realized that although the running mean I calculated in the real notebook yesterday was correct and in the rotated frame, my plots above are NOT in the rotated plane and should be re-made. New plots (for four of the pairs):

Want to figure out the simplest way to convert img_num to time. I think when I sample temperature I can also take the time average for each temperature item, and then plot all graphs against those times instead of image numbers. Updated image:

The scaling on y is difficult, but I can set the distance between ticks to be the same. However, the actual distance between them is different.

The updated figure looks like this:

I also have to subtract off the running mean from the other series of plots (over the course of the night). Doing that now.

That plot now looks like this:

Deciding whether or not to keep the final 11:51-11:59 plot in the sequence.

Now calculating the ellipticity components. We have the position angle calculated, and we calculate rotazel in the same way as before (with calculate_rotazel function). Now, we rotate the points before calculating the ellipticity components. Wondering if we can just rotate the angle?