Plugging Lab Tour

In the morning, Dan and John were swapping the R2 camera. To put it in context, this summer shut down we put the spare dewars on B2 and R2 spectrograph. The calibration tests showed that the both R2 and B2 focal plane is tilted. B2 got it corrected by a shim. But, R2 didn't. So, they are now swapping back the old R2 in place of the new. I spend an hour in the morning trying to see the process. It took a lot of time to pump down the vacuum inside the dewar of R2 that was already on the spectrograph. Below are two pictures of 1) the camera before putting in and 2)the dewars of spectrograph 1.

Today, Frances took me for tour of the plugging lab and the various storages. She explained to me various difficulties that they face during plugging.

Below are the points which I noted which may of help to me.

1. It takes roughly 40 minutes for 2 pluggers to plug an eboss plate from start to end. But, for manga it takes only 20-30 minutes as they have less number of fibers
2. The observatory has three full time pluggers, Diana, Frances and Muwen. They will be available 7.30 to 3.30 on week days and on week ends they take turns. Joshua is a part time plugger, who is available on Fridays and week ends. Tracy Naugle has moved on to more site maintenance works.
3. On weekends, the number of pluggers are decided based on the number of plates to be plugged. If less than two plates, only one plugger comes. For 3-5 plates, 2 pluggers come and for more than 6 plates, 3 pluggers come. So, plugging amendments on week ends should not be later than 8 am MDT(because the number of pluggers are decided on the number of plates). On weekdays, this can be relaxed to 9 am MDT. But, if there is an emergency, Pluggers can accommodate till 2.30 pm.
4. It takes roughly about 15 minutes to mark an eBOSS plate for two persons. No marking is done on weekends
5. APO storage can have a capacity of 356 plates. Cosmic storage is 4 miles away. It is a really abandoned place. it is difficult to reach cosmic, especially during snow. So, plate movement needs to be planned in advance. The temporary storage near Engineer trailer can store up to a maximum of 9 boxes. Each box can contain a maximum of 10 plates
6. The pluglab bay can only hold upto a maximum of 9 carts. There are 4 more dolly's available in case bay has no room. Manga is particular that they do not want the dolly. Their fibres are sensitive. So, eBOSS carts will go to dolly's in case there is not enough room in the Bay
7. Sparse plugging. Only one fibre for 20 holes bundle. The remaining fibers are bagged to ensure that no light goes in to those fibres.
8. Retired plates are just moved to Cosmic storage until the end of SDSS-IV. That means, in a worst case scenario, a retired plate can be called back.