Wednesday, March 28, 2012

Last Eclipse of the Spring Season

Today we had the last eclipse of the Spring 2012 Eclipse Season. Here are 4 images of the Sun at about 0630 UT today. Comparing the upper left image (1600) with the upper right and lower left we see the different ways the Earth's atmosphere absorbs light from the Sun. Ultraviolet light at 1600 Å is absorbed about 105 km above the surface of the Earth while 193 is absorbed at 130 km and 304 at 150 km. (171 is absorbed at 120 km). The 1600 edge is pretty straight while the others are rougher. Changes across the disk of the Sun are important in the other three channels, but the effects of changes in the Earth's atmosphere at 150 km can be seen at the top of the 304 image.

To really see the effects of the Earth's atmosphere you should use difference images. If all of the solar patterns can be determined you can map the Earth's thermosphere with these partial occultations.

Next on the schedule is a ΔV burn today at 2315 UTC (7:15 pm ET).

Tuesday, March 20, 2012

SDO Weekly Report for March 15, 2012

The FOT successfully performed SDO momentum unload maneuver #9 on 3/14. The firing of our thrusters for a few seconds is sufficient to keep our reaction wheels within safe speeds. (Here is a thruster being tested before launch.)

No comet was seen last week, either in AIA or emerging from perihelion in the various coronagraphs. Lovejoy continues as the only Kreutz comet to survive perihelion in the SOHO era. SDO is not in a good position to see Kreutz comets, they approach from behind and must survive perihelion to be visible. From June to December we will be in a better vantage point for seeing comets disintegrate in the solar corona.

Tuesday, March 13, 2012

Another Comet?

SOHO and STEREO are reporting another Kruetz comet moving toward the Sun. It is expected to make its closest approach to the Sun tomorrow, March 14. If it survives perihelion and is bright enough, we would see this comet appearing in the upper right side of the Sun and moving down over the disk. Current estimates are that this comet is smaller than Lovejoy. At this time we do not know the time of perihelion passage.

We have a daily eclipse of the Sun by the Earth (at 0630-0730 UTC tomorrow), and a momentum management burn tomorrow at from 1845-1915 UTC. During both periods the images of the Sun may be absent.

Monday, March 12, 2012

EVE CCD Bakeouts his Week

We will be baking out the MEGS CCDs this week starting Monday, March 12, 2012 at about 1400 UT. This will mean no science data from MEGS-A and MEGS-B during the warmup, bakeout, and recovery sometime Wednesday, March 14. ESP is not affected by the bakeout and will continue to produce science data.

Bakeouts are a normal and essential part of maintaining the accuracy and sensitivity of an on-orbit spectrometer. Even small amounts of contamination sitting on the chip can reduce the measured solar signal. Heating up the CCDs drives the contaminants off the CCDs and reduces the effect.

Thursday, March 8, 2012

Major Geomagnetic Storm Coming?

This morning major news organizations are reporting on the possible geomagnetic storm associated with the flares seen earlier this week.

Examples: BBC News, CBS News, and The Washington Post. Most use an SDO image to show the flare!

Wednesday, March 7, 2012

Another X-class Flare!

At 00:28 UTC this morning we saw another X-class flare from active region 11429. Here are pictures in 1700 (left) and 1600 (right) showing the two ribbons of this flare. This X5.4 flare lasted long enough to be easily seen in the browse image movies on the SDO website.

Tuesday, March 6, 2012

Eclipse Season Starts Today

March 6, 2012 marks the beginning of the SDO Spring Eclipse Season. For the next three weeks the Earth will pass between SDO and Sun at about midnight Boulder time. The length of the occultation will vary from short to almost 72 minutes. Thee eclipses are a normal part of life in a geosynchronous orbit.

The AIA data is currently stale (i.e., delayed) but the problem is being looked at.

Monday, March 5, 2012

X-class flare this morning

An X-class flare occurred in Active Region 11429 this morning at about 0400 UTC (or last night at 11:00 pm ET). Here is the EVE spaceweather feed showing the Sun brightening. Stayed tuned for more images!

Here is a picture of the X1.1 flare at 04:00:32 UT today. You can clearly see the two ribbons that form along the flare. This image is in light at a wavelength of 1700 Å, in the ultraviolet. It measures the response of the chromosphere rather the corona seen in the shorter wavelength channels.

Friday, March 2, 2012

The Think Scientifically Books are Out

The first two Think Scientifically books are available from SDO Educators Website. Each book focuses on a key science theme and includes a hands-on science lesson, math and language arts activities, and other educational resources that can be easily utilized in the classroom. The books are based on national standards and were written by teachers. Both books can be downloaded as pdf files from this website.

SDO began High Gain Antenna (HGA) handover season on February 23 and all handovers have been successful since then. The FOT is ready for the beginning of eclipse season on March 6. The next momentum unload maneuver in scheduled for March 14.