SDSS Science Survey Archive

To find out about all the objects on your plate access the SDSS Science Archive Survey (SAS) site by clicking the button below. Enter your plate number in the box under PlateID(s) to find your plate. On the table below the search box an entry should appear with some information about your plate.

The relevant columns are explained below:

• PlateID: unique integer used to identify the plate
• MJD: integer denoting the night of observation
• RA and Dec: coordinates of the area of the sky that the plate covers
• Survey and Program: name of the survey and program the plate is associated with within the SDSS
• Quality: sometimes searching a plateID might output more than one result, look for the row with good quality
• Spectra: click on the eye symbol below Spectra to output a list of all the objects on your plate.

You will be taken to the page below which shows a list of all 1000 objects on your plate:

Here we have some of the same columns as above such as PlateID, MJD, RA and Dec. In addition to those, some other important categories include:

• FiberID: number of the optical fibre connected to that hole
• specobj_id: unique number that identifies the object observed
• z: redshift of the object
• Class: type of object – QSO (quasar), STAR or GALAXY

To learn more about a specific object on your plate click on the icons in the column called Plot. This should take you to another page with a plot of the spectrum as well as some information including the coordinates (RA and Dec) and type of the object selected.

DESI Legacy Survey Sky Browser

Another way to find all the objects on your plate is using an SQL search. You can learn more about SQL searches and how to use them in the Finding Information About an Object page.

In this method we use an SQL search to obtain a CSV file with all the objects on your plate. Then, we upload this file to the DESI navigator to obtain a map of all the objects on your plate.

Access the SQL Search by clicking on the button below, clear the code in the box and replace it with the code below. Replace the XXXX below with your plate number and select CSV for the output format.

select top 1000 spa.ra, spa.dec, spa.dered_r as magnitude, spa.class, spa.z, soa.xfocal as x, soa.yfocal as y 
from specphotoAll as spa
join specObjAll as soa on soa.specObjID = spa.specObjID
where spa.plate = XXXX and spa.dered_r > 0
order by spa.dered_r asc

Now, access the DESI navigator by clicking the DESI button below. Click choose file on the bottom left of the screen and select your CSV file, press upload. You should end up with something similar to the image below. The objects highlighted in green are the 1000 objects on your plate.