The Beehive Cluster / Praesepe M 44 in constellation cancer and seven asteroids

Messier 44, also known as the Beehive Cluster or Praesepe, is a bright and prominent open star cluster located in the constellation Cancer. It is located approximately 610 light-years away from Earth. It is one of the closest open star clusters to our solar system. As the cluster lies close to the ecliptic, asteroids from the solar system can often be observed in its vicinity, depending on the date of capture.


M 44 and seven asteroids, image data: f=430mm, f/3.3 35x180s Canon EOS 6Da ISO800

Messier 44 is a relatively young cluster, estimated to be around 600-700 million years old. The stars within the cluster were born from the same giant molecular cloud. It was one of the first deep-sky objects studied by Galileo Galilei in 1609, who counted around 40 stars in the cluster. It was later added to Charles Messier's famous catalog of comet-like objects in 1769. In September 2012, two planets which orbit separate stars were discovered in the Beehive Cluster. The finding was significant for being the first planets detected orbiting stars like Earth's Sun that were situated in stellar clusters. Planets had previously been detected in such clusters, but not orbiting stars like the Sun.

But there is more to the image presented in this blog than "only Messier 44": the open cluster is located close to the ecliptic where asteroids populate the planetary disk about the sun. And therefore, in the foreground it happened by chance that 7 asteroids were captured within the image. In the standard processing of deep-sky images the pixels stacks are statistically evaluated when multiple light images are averaged. Usually bright pixels which show up on only one or two images are detected as outliers and replaced by the average or median value. Therefore, asteroids and objects moving on celestial background often go undetected. In this case a colleague from Hofheim observatory made me aware of the high likeliness to have captured asteroids in the exposures - et voilà after sum nasty processing with manual hot-pixel removal some asteroids showed up as can be seen in the image below where cut-outs of detail frames are marked:


Image with marked cut-outs showing asteroids (in the foreground)

Seven Asteroids moving in the field of view

1497 Tampere
(mag. 16.07)

1618 Dawn
(mag. 15.49)

18693 1998 HS19
(mag. 16.89)

1100 Arnica
(mag. 15.50)

1819 Laputa
(mag. 15.96)

16461 1990 BO
(mag. 16.78)

7755 Haute-Provence
(mag. 17.17)
A1: 1497 Tampere (m 16.07)
A2: 1618 Dawn (m 15.49)
A3: 18693 1998 HS19 (m 16.89)
A4: 1100 Arnica (m 15.50)
A5: Laputa (m 15.96)
A6: 16461 1990 BO (m 16.78)
A7: 7755 Haute-Provence (m 17.17)

Exposure Data:
  • Telescope: Corrected Newton, f=430mm, f/3.3

  • Camera Canon EOS 60Da ISO800

  • Exposure Times
    • 35x180s

  • Total: 1h 45min

  • Date: 11.01.2024 ca. 3h UTC

  • Location: Bad Kreuznach / Germany

  • Mount Skywatcher EQ8R-pro / Pegasus Astro EQMod

  • Guiding and Exposure Control with INDI / PHD2 / CCDCiel running on XUbuntu Linux

  • Image Processing PixInsight and Darktable