Annular solar eclipse seen in mm-wave (May 21, 2012)

Photos of the annular eclipse at a public event held at Osaka Prefecture University. (taken by Toshikazu Onishi)

- About the observation

In mm wavelength, we can observe thermal emission from various kinds of objects. The Moon is then observed as emission even at new moon with a temperature of ~ 200K although the Sun is observed at ~ 6000K. We were lucky in a sense that our telescope is located in this annular eclipse area , the telescope is created so as to achieve quick large-scale survey of molecular clouds, and the sky was very clear at the time even at this season when summer is approaching.

One of the images we took with 1.85m telescope. The red disk at the center is the Sun, and the cyan disk is the Moon. The colors are assigned according to the temperature; blue, cyan, yellow, and red from low-temperature to high-temperature. The temperature data is log-scaled before the color assignment.

- Sequence images of the eclipse

The observed time is indicated at the top of each image. The time 7:36 is the time of the annular eclipse.

- Comparison: mm image and visible photo

- Movie

Converted the sequence images to a movie: Link (MPEG4, WMV)

- About the 1.85 mm-submm telescope

We have developed the 1.85m mm-submm telescope to improve our understandings of the physical conditions of molecular clouds. The target frequency is around 230GHz corresponding to those of molecular rotational lines of J=2-1 of carbon monoxide and the isotopes (12CO, 13CO, C18O). The 2.7 arcmin beam size (FWHM) of the telescope is suitable to obtain a large scale distribution of molecular gas which also can be compared with large-scale observation data in various wavelengths e.g., Planck, Spitzer, Fermi, and so on. In January 2011, scientific observations have successfully started . We just installed the receiver to obtain both polarizations simultaneously by using OMT, and then the observing efficiency will be doubled.

Please check this PDF file for the details.

The 1.85m telescope installed at Nobeyama Radio Observatory without dome (left) and with dome (right).

- Other information

Click images to enlarge. You may use the still images and the movie for educational or informational purposes with a credit: "Radio Astronomy Group, Osaka Prefecture University".

Observation and data reduction: Atsushi Nishimura (PhD student)

Written by Toshikazu Onishi

Contact address: AnnularEclipse __at__ s.osakafu-u.ac.jp.

Japanese page

Created: May 25, 2012