The Sky Guide Challenge
Do the Hubble Deep Space Field-lite.
The Hubble Deep Field (HDF) is an amazing image which brought home how incredible our Universe really is. It consisted of 342 separate exposures taken by the Hubble Space Telescope (HST) over 18-28 December 1995. The combined result produced an unprecedented look into deepest space. The target area was a rather bland section of Ursa Major approximately one 24-millionth
the area of the entire sky. Despite measuring just 2.6 arcminutes across, around 3,000 distant galaxies fill the frame.
The original HDF target area lies just north of the Plough asterism. As this is currently well placed in the UK’s night sky, we thought trying to replicate the HDF would be a good challenge. Okay, unless you own your own space telescope, it’s not going to happen, but you should be able to record some of the brighter objects visible in the original image. This is best-suited to a CCD/telescope combination but other combinations may work too. And it’s not limited to large apertures either, so any setup should reveal something of the HDF.
The first issue is locating the correct bit of sky. As it was specifically chosen because it looked empty, you’ll need to employ a bit of star hopping to get there. Use stars Alioth and Megrez as your starting point. From there navigate to the two 6th magnitude stars we’ve labelled A (HIP 62402) and B (HIP 61936, or 76 Ursae Majoris). Use these as shown to navigate to the correct bit of sky.
The Hubble Deep Field covers an area 2.6x2.6 arcminutes, roughly 1/12th the apparent diameter of the Moon. A setup covering an image area of 30 arcminutes or smaller is recommended and you’ll need good tracking or preferably autoguiding to avoid long exposure trailing. We suggest exposure times in excess of 900 seconds.
As ever, experiment with your exposures to see what works best for you. Image registration and stacking will definitely help smooth out some of the noise that gets in the way and we recommend a full calibration sweep of darks, flats and bias correction.
The original HDF revealed how vast our Universe truly is. Your own version of the HDF will reveal how much of that Universe is available for even modest equipment to image. Don’t forget to send your results in to our Hotshots gallery (see page 28).
You won’t be able to match the glory of the original HDF with your equipment but you might be surprised how much you can capture
Locate the two stars labelled A and B to help you focus in on the correct HDF area
The HDF field imaged with a 4-inch refractor and CCD camera showing features down to at least mag. +22.25