What is the red line across the top?

• by atanauli

  Posted May 26, 2014 5:28 PM

• by JeanTate in response to atanauli's comment.

  Welcome to Galaxy Zoo, atanauli!

  That's a satellite trail, sunlight reflected off a satellite that just happened to pass through the field of view of the SDSS camera at the time. In other words, an artifact. More common trails are green, and there are also blue ones; would you care to suggest an answer as to why?

  Happy hunting! 😃

  Posted May 26, 2014 6:33 PM

• by atanauli

  Something to do with redshift or doppler effect ?? -- The satellite was moving away from the SDSS camera. Thanks for the Welcome message. This seems fun. Looking forward to seeing an alien face.

  Posted May 26, 2014 11:02 PM

• by ElisabethB moderator

  Nope, nothing to do with redshift ! The satellite got caught in the red filter. It could just as easily have been the green or blue one !

  Posted May 26, 2014 11:07 PM

• by JeanTate

  To add a bit to what Els wrote ... the SDSS camera has five filters (called u, g, r, i, and z), and the RGB JPEG images we see, here in Galaxy Zoo, are constructed from what the camera recorded by the CCDs behind the g (the B channel), r (G), and i (R) filters. More about the amazing SDSS camera (and spectrograph) here.

  Posted May 27, 2014 10:37 AM