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Jon Greif

Location of Photo:

Alpine and La Jolla, CA, USA

Date/Time of photo:

Multiple nights between September, 2022, and July, 2023


Takahashi FSQ-85ED with 1.01x flattener/reducer. ZWO ASI533MC Pro imaging camera. Optolong L-Pro filter. Rainbow Astro RST-135 Mount. ZWO 30mm Mini Guide Scope with ZWO ASI290 Mini guide camera. ASIAIR Plus controller. Processed in Pixinsight 1.8.9.


This is the Andromeda Galaxy, catalogued by Messier in 1764 as M31, and represents 14.4 hours of exposure time over multiple nights between last September and last week, some from La Jolla and some from Alpine. The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to our own Milky Way. Andromeda has a diameter of about 152,000 light-years and is approximately 2.5 million light-years from Earth. The galaxy's name stems from the area of thesky in which it appears, the constellation Andromeda, which itself is named after the princess who was the wife of Perseus in Greek mythology. The Milky Way and Andromeda galaxies are expected to collide in around 4–5 billion years, merging to form a giant elliptical galaxy. The Andromeda Galaxy is among the brightest deep sky objects and is visible to the naked eye from Earth on dark, clear nights, even when viewed from areas with moderate light pollution, and, in fact, was known to the ancients. Around the year 964, the Persian astronomer Abd al-Rahman al-Sufi was the first to formally describe the Andromeda Galaxy. He referred to it in his Book of Fixed Stars as a "nebulous smear" or "small cloud".