Dates: September 10 -29, 2023

Things to follow up on after the trip

Notes from Chris:

design baffle for top of chimney. Need bolt and flange drawing and desired aperture. Get it made by Nov visit.
do analysis of focus sweep from Sept 26 run, and build focus analysis tool. Header keyword is distinctive.
complete quantitative analysis of stray and scattered light, including contrast determination, from pinhole data. Write technote.
consider asking Marc to make a sky spectrum mask. For us that would be on right half of detector, since we now do offsets?
revise Eske’s quadband analysis code to accommodate multi-amp offsets (should be easy)
Get Tiago to implement lookup table revisions based on writeup.

Trip Planning

CWS to bring:

slits that can mount in pinhole mask mount
other pinholes from lab

To bring:

2 AuxTel pinhole holders (with black coating)
1/2" pinholes + retaining rings
1" pinholes + retaining rings
1/2" light blocks
1" light block (shouldn't need it though)
foil (some cut, some not - probably cut at 36 x 60 mm)
superglue
cutter for foil
spanner wrench
adhesive black just in case

Tests to run/things to do while in Chile

Get DIMSUM running continuously for ~10+ days (maybe a few bursts every 10 minutes)
Install AuxTel pinhole holders
Install mask on quad notch filter
- Make sure it's on the correct side!!!!
Run tests with AuxTel pinholes
- During day, with lights off, look for scattered light
- Look at flat field screen and see how flat it is as function of wavelength
- At night, take images with different pointings, different distances from moon, and try to find the waffle (or try to image the waffle, and then image with the pinhole)
Figure out where in the dome (or on the TMA) the CBP calibration hardware will go
Use laser imaging to get full layout of dome (this may exist)
Export laser + Keysight synchronization options (note: PTP/NTP are not viable options)

Note on applying black coatings/covers:

After a fair amount of experimentation (and some blood), I think it is best to cut and apply the black sheets onsite. It won't take very long and we don't risk the black getting scratched. Furthermore, it will allow us to cover the pinhole mask after we decide which size we want and put the pinhole in, making only a small hole in the center of the mask.

Log

What I brought in the end:

3 sheets of adhesive Acktar black coating
1 each of 100, 200, 500, 1000 um 1/2" pinholes
1 each of 50, 1000, 2000 um 1" pinholes
20 1/2" retaining rings
3 1" retaining rings
2 designed pinhole holders
5 SM05PL 1/2" light blocks
1 SM1CP2M 1" light block (even though this is unnecessary)
Some latex gloves
sharp scissors
Crazy superglue
spanner wrench
1 straight edge cutter

What pinhole configuration we will install

Installation will happen the second or third week of the visit

We will install one central pinhole. The optimal pinhole diameter for highest resolution is given by the Fraunhofer approximation: d = 1.562 * sqrt(lambda * f), where f is the distance to the imaging screen. If lambda = 550 nm, then d = 1.562 * sqrt(550e-6 mm * 230 mm) = 0.556 mm, so about 500 um. We may move closer or further away, and we could work at longer wavelengths. So I think 1 mm should be fine, as is 500 um. I'll plan on installing the 1 mm pinhole in the 1" slot, unless Chris brings the 500 um pinhole in time.

What quadnotch mask size we will use

The disperser slot size is 60 mm x 60 mm. The disperser wheel is 230 mm from the CCD. We want to block 0th order light on half of the disperser. We have an f/18 beam so 230 mm away the size of the spot is 230/18 = 12.8 mm. So I will create a mask that is 30 mm + 6.4 mm rounded to 37 mm wide. Thus the total dimensions are 60 mm x 37 mm.

Update: I spoke to Marc and they have a spare mask, so I will try to use that instead. That way we don't use anything that touches the glass.

Tuesday, September 12

Meeting in the morning about installing hardware in the dome. There are still a lot of unanswered questions about where the flat field screen will first be assembled and how (and when) it will be installed.

Checked with Marc that the pinhole holders fit in the disperser frame. They do!

Drove down to the guard station with Parker, Chuck, and Jacque to look at the flat field screen. It's there and does not seem damaged. No mold or poop or anything. However, the pieces of the screen shifted and lean on each other instead of standing straight. It's probably okay.

Visited the main telescope dome to discuss where to mount the CBP calibration system. Chuck suggests the upper pylons, because they have attachments that will allow a breadboard to be mounted. Some notes:

Have to get the exact dimensions for the breadboard mounting space from Chuck. The sketch exists.
The upper pylon is above where the CBP will be mounted. We have to think about that and will have to wedge the system so it's at the correct angle (and confirm the beam won't be clipped by the TMA).
It's very dusty. We need a good dust cover.
There is a chance the pylons will have to be used for passive damping, in which case we have to mount it elsewhere.
We haven't figured out where to mount the Keysight and possibly computer.

Observing run: tried out quadnotch with new mask in the filter wheel and it worked great!

We will install the mask directly on the quadnotch filter tomorrow.

We also tried the cylinder lens. It looked okay but needs to be cleaned because there's a fair amount of horizontal structure on this and the holograms that is the same.

Wednesday, September 13

We installed a mask that Marc brought (specifically, a centered on) directly on the quadnotch disperser.

It worked well!

We also had meetings with the safety crew on summit to discuss laser safety.

September 14

Made the pinhole mask. Will install it tomorrow morning. It's a 1 mm pinhole and a black adhesive on both sides with an adhesive radius of between 2-3 mm, allowing for > 30 degree field of view, which should be plenty.

Tried to get the DIMM working tonight. Brief notes on what failed: Latitude and longitude were wrong. GPS broked. Couldn’t set longitude and latitude using instructions in the manual. Then couldn’t make things work in manual mode - quite possible the mount never moved (although I also turned off the mount in vimba viewer). Ioana will go through the logs and add details to the obs ticket in the morning.

September 15

Installed the pinhole in the grating wheel.

Tried to set things up so we could take an image of the flat field screen with the pinhole. That meant first fixing the white light dome illuminator so that it would open and close without throwing errors. I had to adjust the pivot point of the shutter and the location of the limit switches. I adjusted one too far (or it was too low) and the shutter arm broke it when it moved past. We will possibly install a new limit switch but for now there's a software workaround - we just ignore the errors. Then we tried to take pinhole images but there were configuration issues with LATISS. We will debug next week.

I worked on setting up DIMSUM again, now that people aren't so actively moving around it to change out the filters. However, it requires new AA batteries and I couldn't locate any. I will acquire more. I did verify that we can connect to the Mac and control the camera and take pictures remotely.

September 21

Did observing with pinhole and took images of waffle. See AuxTel night log

September 22

Repointed and refocused and changed batteries and set up DIMSUM to take two bursts separated by a few seconds every 10 minutes until late afternoon on Monday (this is achieved by running the full suite of take burst commands twice with a one second wait time in between and then waiting 10 minutes). Also did refocusing and repointing. The focusing is not perfect, but it is ~Gaussian, and it's the best I could do while still setting things up to go down on the bus.

September 25

Tilted quadnotch filter back to the left slightly to hopefully correct for the tilt to the right.

Attempted to install SDSSi_65mm filter in place of the pinhole, but it didn't fit in the disperser wheel. Roberto will modify the disperser holder appropriately.

Took measurements of M2 reflectivity. Confirmed it's silver.

Also took lots of photos of the AuxTel mirrors and baffling. There are certainly quite a few glinty screws and holes that could explain the waffles and things we see with the pinhole.

Tuesday, September 26

Got DIMSUM working again. The battery on the receiver died so not all images from the weekend run were good. I didn't have time, given AuxTel availability, to tune the focus, and it's drifted a bit. But it's not a donut and will hopefully be okay to analyze.

Did pinhole analysis work. See the pinhole confluence page and the presentation I gave today: https://confluence.lsstcorp.org/display/LTS/AuxTel+Pinhole

For the observing run tonight we are going to see if the tilt worked or if we went too far.

We also are going to take the quadnotch data with each image per triplet on a different amplifier.

Except unfortunately it seems like it might be too windy...

We managed to get some data at around 1am! We're now taking 60s exposures as well, and it seems like the tilt is not as bad. See images 548-550:

Wednesday, September 27

Worked with Edison Bustos. Worked on two things.

For the dual band GPS receiver, he showed us the antenna he suggests we mount it on.
For the DIMM, we opened up the electrical tried the spare GPS receiver. It gave a red blinking light, the same as the other one. We left it outside the box and then Michael Ruder checked remotely and saw that the GPS was working. I will try tonight to develop a new pointing model for it.

Talked to Mario about installing a baffle at the top of the chimney. He was open to it but wished there were more than 2 holes. He will do more careful measurements of the size of the holes later. He also said we could but sharpie on the exposed shiny screws at the base of the chimney. Erik doesn't think that will work for red light, but it's easy and a good start. He also gave permission for us to put our pinholes and supplies in their optics box.

Talked to Marc about the alignment of the quadnotch mask. It seems like it's a bit smaller than expected. Here is quadnotch image 550 from last night (so very close to full moon), with very minimal ISR (bias and defects removed and that's pretty much it). I took the median of columns 2000-3500 and plotted them. You can see in the zoom that the cutoff from the mask starts at just after 300. He was aiming for closer to 500. Depending on our star placement, this could mean we cut off a little bit of light... Marc is going to make masks with slightly larger holes. We can decide if we want to install them or not.

Also, it's a great sky spectrum.

Talking to Aaron Roodman as well about how to make holes for the CBP mask. He says: We made both cut and lithographic holes (big ones) for the x-talk projector. See Figure 6 of https://arxiv.org/pdf/2101.01281.pdf for the images from this projector - which used a collimated beam through the ~1mm holes. The lithographic one did have significant reflections and we ended up not using it. We did not use sheet metal, but rather thicker stock for the holes such that flatness was not an issue. I think we did have these laser cut, but am not positive - need to ask Adam Snyder. I do recall that we looked at the holes under a microscope and needed 2 iterations to get decent results. Even with that there were still small imperfections in the holes that produced diffraction, at least at the 1e-4 level which we needed for xtalk studies.I had looked into electron beam or wire-EDM hole drilling, but we didn’t pursue those - that might yield better results. I'm following up with Adam Snyder.

September 28, 2023

I noticed that DIMSUM had stopped flashing and was just taking black images. I changed the batteries in both the transmitter and receiver, but then realized that the flash still wasn't going off. I found that someone had unplugged it and I plugged it back in. Now it works.

Craig installed the limit switches that Chris brought on the AT white light shutter. It works much better now.

I left all the pinhole material, including the spare adhesive black and the cutter for it on the shelf in the cabinet with the other AuxTel filters and dispersers. Our box didn't fit in their box, but it's right next to it.

I left the spare AA batteries in the tool cabinet near the AuxTel telescope, in case we want someone to change the batteries.

I added more stars to the DIMM pointing model. I still couldn't save the whole model on the server, but I saved it locally. The rms error was 7.41 arcsec. I let Brian and Michael know and hopefully one of them will save it and then get the DIMM to run more regularly. See the jira ticket for more details. https://jira.lsstcorp.org/browse/SUMMIT-4539

I was in a very long meeting on v&v with Keith and Jeff. I tried during that time to get Erik to sweep the y offset of the disperser but was unsuccessful. The concern is that we are right at the edge of where the light gets blocked. We're at 300 pixels, but it would probably be safer to be at 200 pixels, based on the plots from yesterday and discussions with Marc. That said, I will get the drawings from Marc, and he is planning on making a larger one anyway because the exact y position matters more for the hologram. Then we can make our own and perhaps also do the narrow region to get the sky spectrum.

October 8, 2023

Got the DIMSUM working again (new batteries). Played around a while trying to improve alignment of the camera. I wasn't successful (I made it worse, then got it back to about the same). I wonder if it's gotten worse with all of the temperature changes in the dome over the past nine months. I'm repeating the two rounds every 10 minutes 1100 times, so hopefully this will keep running through the observing run next week.

stubbslab

Elana's September Trip to Chile