Eclipse Season

Eclipse Season

On this Page:

Finding Eclipse Times and Durations
Tracking Eclipse Settings
IDL plots
S/C Battery Voltage Adjustments
EGSE Eclipse Limits
Other Eclipse Operations
CCD bump
clocks
Post Eclipse Summaries

Finding Eclipse Times and Durations

The MOC will post a document that can be found in the FDS Products/shortterm directory SDO MOC Files > fds products > shortterm called ECLIPSE_yyyyddd.S00 (or something). It will look like this:

There is also another type of file called ECLIPSEATM_yyyyddd or something, which is nice because it doesn't have all of the extra columns. You do have to select the right grazing height for the limb of hte earth though (0 km), which should be the last section in the file.
For a night with a full eclipse there are three lines: penumbra, umbra, and then penumbra again, for each stage of the eclipse.
Copy this file to a text file, and get rid of any lines for incomplete eclipses (i.e. only penumbra) and any colums that are not "start time", "stop time", and "current condition". Also remove any header lines. Your input file should look like this:

Now run the IDL program "convert_times.pro", which will read in this input file and creaste a file with dates and times in a readable format:

IDL> convert_times, 'infile.txt'

IDL>

You will get a file that looks like this:

Tracking Eclipse Settings

As of September 2011, we continue to change things (temperatures, time, focus sweeps, etc) to help us optomize AIA and HMI recovery after an eclipse. The team page has spreadsheets with all the eclipse settings for each night, along with any notes about results, who is on-call, special sequences, etc. Pull a new document number each eclipse season, and update the spreadsheet daily or as needed. It is also sometimes useful to pull a child document number to keep track of IDL plots of the temperatures from each night.
Per the thermal meeting on 30-Jan-2011, we will reconsider performing focus sweeps on AIA following every eclipse for the March 2012 eclipse season.

Eclipse Season Settings and Plots
September 2010		AIA	HMI
March 2011		AIA	HMI
September 2011		AIA	HMI
March 2012		AIA	HMI

After changing any heater zone parameter, you should always update the HMI Thermal History Spreadsheet.

IDL Plots

The morning after each eclipse, you can make thermal plots and pointing plots using the routines:

aia_eclipse.pro
aia_pointing.pro
hmi_eclipse.pro

These plots can be posted to the eclipse information docs on the team sites. You may also want to send it out to people if it is especially interesting or merits a change in the settings for the next night.

Spacecraft Battery Voltage Changes

About three days prior to the start of eclipse season, and three days after eclipse season, the MOC adjusts the battery voltage to accomodate increased energy demands during eclipse season. The change is generally from 31.5 V to 33.1 V pre eclipse season, and 33.1 V to 31.5 V post-eclipse season. The changing voltage affects the temperatures in HMI's heater zones, which are regulated only by duty cycle.
After you adjust the duty cycles to accomodate the voltage change, it is good to do a focus sweep to make sure the temperatures did not change the best focus position.

Battery voltage decrease and affect on HMI post-eclipse season:

On HMI, duty cycles and durations are adjusted to keep temperatures constant after the spacecraft increases its battery voltage for eclipse season. The new duty cycles should be:
The actual duty cycle can be found using the giant spreadsheet in the JSOC-IOC, or by using the formula:
Or, again (as in the section above), by using the IDL routine battery_voltage_change.pro:

IDL> battery_voltage_change

Please enter the current Deadband Duty Cycle(s) in the form "dc1, dc2, dc3, ...dc7": 22,4,19,10,47,4,81

Please enter the current Duty Cycle Duration(s) in the form "dur1, dur2, dur3, ...dur7": 37,26,26,25,15,25,16

Please enter the current spacecraft battery voltage (likely 31.5 or 33.1): 31.5

Please enter the new spacecraft battery voltage (likely 31.5 or 33.1): 33.1

Note: output format is (Deadband DC, DC Duration, Actual DC)

		
Zone 1: Target DC:  19.581836
        Current:   (22, 37, 21.621622)
        Suggested: (20, 46, 19.565217)

Zone 2: Target DC:  3.4833074
        Current:   ( 4, 26, 3.8461538)
        Suggested: ( 4, 29, 3.4482759)

Zone 3: Target DC:  17.416537
        Current:   (19, 26, 19.230769)
        Suggested: (18, 23, 17.391304)

Zone 4: Target DC:  10.867919
        Current:   (10, 25, 12.000000)
        Suggested: (11, 46, 10.869565)

Zone 5: Target DC:  42.264129
        Current:   (47, 15, 46.666667)
        Suggested: (43, 45, 42.222222)

Zone 6: Target DC:  3.6226397
        Current:   ( 4, 25, 4.0000000)
        Suggested: ( 4, 28, 3.5714286)

Zone 7: Target DC:  73.584868
        Current:   (81, 16, 81.250000)
        Suggested: (74, 34, 73.529412)

IDL>

Before: Voltage = 31.5 V					After: Voltage = 33.1 V
Zone	DC	DUR	Actual DC (%)		Zone	DC	DUR	Actual DC (%)
1	22	37	21.62		1	20	46	19.57
2	4	26	3.85		2	3	29	3.45
3	19	26	19.23		3	17	23	17.39
4	10	25	12.00		4	11	55	10.91
5	47	15	46.67		5	42	26	42.31
6	4	25	4.00		6	4	28	3.57
7	81	16	81.25		7	74	53	73.58

Changing Duty Cycles

Please Note: After changing any heater zone parameter, you should always update the HMI Thermal History Spreadsheet.

EGSE Limits

The EGSE limits will need to be changed to the eclipse versions using the STOL [aia/hmi/sdp]_change_tm_limits) on the IOC, SDP, and MOC machines. There are options in the STOLs for "eclipse season limits" see How to Update EGSE Limits for a refresher.
As of August 2011, HMI does not have a separate set of eclipse limits. AIA eclipse Limits (aia_eclipse_limits.src) differ from aia_nom_ops_limits in the Forward heaters (TS04, TS06, TS17, TS19, TS30, TS32, TS43, TS45), Secondary mirror temperatures (TS02, TS15, TS28, TS41), and FAA temperatures (TS07, TS20, TS33, TS46). This information should be tracked in the comments section at the top of the aia_eclipse_limits STOL

Other Eclipse Operations

Run a bunch of detunes (HMI)

The CCD Bump

About 3 weeks or so before the start of eclipse season, you will see a daily "bump", and allover "boost" in the temperature profile of the CCDs. The effect is visible in other temperatures as well, but is most pronounced in the CCD plots. The AIA bump starts showing a day before the HMI bump does.

Clock Issues

The clocks will require a bit more attention during eclipse season because of the fluctuating temperatures.
They will react to the battery voltage changes before and after eclipse season. The battery voltage invrease at the start of eclipse season acts like an adjustment of roughly -1 DN (so it slows down the clocks by about 10 ms/day).
The clocks will tend to run faster than usual during eclipse season because of the temperature drops during the eclipse.
At the end of eclipse season, the clock will slow down significantly because the temperatures will be warmer and steady. Make sure there is lots of room for error if you are leaving the clock over the weekend, and bump it up one more than you think it should go.

Post Eclipse Summaries

A set of post-eclipse summaries are usually produced at the end of eclipse season and added to the team sites.
The summaries include plots of thermal systems, power usage, HMI focus, and AIA pointing variations through eclipse times. Text files of plotted data and spreadsheets detailing programs run and changes made during eclipse season are also uploaded to the sites.
Instructions for producing the post-eclipse summaries and a checklist for eclipse season can be found in the file post_eclipse_plot_instructions2018.rtf on the more recent AIA eclipse summary pages such as the 2020 eclipse summary page. A full list of the team site document numbers for AIA and HMI eclipse summaries are in the instruction document. Note: The instructions and checklists are subject to change, so check the latest summary sites.