Imaging Uranus and Neptune with a small telescope

 Hi gang.  So the last couple of weeks - the end of August and beginning of September between the smoky skies here in western Canada and between imaging Jupiter and Saturn once they are high enough in sky usually around 2:30am in the early morning it is time to start imaging our 2 farthest planets in our solar system.  There are several challenges with imaging both of these dim planets.  Uranus is a bit easier to capture than Neptune since it is a bit brighter.  Due to our sky conditions (smoke and lots of haze in the sky and light pollution) right now it is impossible to see either planet with your eyes are there are only a few visible stars in these conditions in the area of either of these planets.  So to solve these issues I use a Celestron computerized alt-az goto tracking mount to locate these planets.  First you need to use either 3 star skyalign (the most accurate mode) or planetary align on one of the bright planets like Jupiter or Saturn to calibrate and setup tracking on the telescope to get to the general area of these planets.  Now with a higher focal length telescope like my Celestron Mak which has a focal length of 1350mm the field is much too narrow you will not be able to accurately goto to these planets properly.  The Celestron astrofi and Celestron Nextstar systems are designed to work well with telescopes 650mm and lower and usually with 20mm eyepieces.  So there is a good solution for higher focal length telescopes like my Mak is to use nearby stars and to resync to these stars in the areas of the planets to greatly improve goto accuracy.  The other and my preferred method is just to use the "precise goto" function on the hand controller which basically makes you goto to a nearby meduim bright star whcih usually shows up in the edge of the field of view then you center it in sharpcap with the crosshairs then hit enter and voila the telescope will automatically just to the planet accurate usually within the field or view and sometimes dead center. So that is basically lesson 101 in usually Celestron Astrofi and Nextstar mounts accurately to find very small and dim targets with high focal length telescopes accurately.  Of course make sure your finderscope is calibrated accurately in the first place so you can quickly locate the stars it jumps to for calibration and precise goto's or you will have nothing but problems. 

So my first target after imaging Saturn for the night next is to image Neptune as it is not too far off and I already have planetary tracking going.  After doing a star sync and previse goto (as described above) I center Neptune which is very dim into the center of the camera view in Sharpcap and take several captures with various exposures and gains.  it is almost impossible in Sharpcap to use the histogram to dtermine the correct or optimal exposure for these super small dim planets.  Some trial error is involved taking various exposures and gains to find the optimal images afterwards.  Now if you are lucky and conditions are just right you might just be able to get Neptune's farthest and brightest moon Triton as well.

Next I usually move to the back of my yard recalibrate everything again as above and image Jupiter then I look for Uranus which is fairly close by.  If conditions are very clear and dark you can just barely see Uranus with your eyes but I am not so lucky due to sky conditions currently.  So I again use the procedure outlined above and voila Uranus in the camera field of view.  Now again if you are lucky and get the exposure high enough you can get several of Uranus moons as well.  Just like Neptune above I take various captures at different exposures and gains for the same reasons as Neptune.  The histogram does not work well on these planets for reliable imaging and is misleading.  Also to get the dimmer moons you need to take higher exposures which of course blows the planets exposures out but that's ok if you are trying to get the moons as well.  So having multiple exposures makes a lot of sense for postprocessing.

Ok here are some captures of managed to get of Uranus and Neptune over the last couple of weeks.  I used my Celestron 102 Mak, my smaller Orion 80mm goscope and a planetary camera with various exposures and gains on the telescopes to get these images.  I postprocessed with Astrosurface, Siril, Registax for sharpening and Wavesharp for enalarging the very tiny images of these planets.  And finally GIMP is great for cleaning up the color and contrast of the images.

Captures of Uranus:

Uranus through Mak 102mm scope

Larger image of Uranus above

Larger yet

Supersized Uranus (10X its original size)

Uranus and its pole with 102 Mak

Another pole image with Uranus

Uranus and 3 of its Moon with the 80mm Orion Goscope wideview

The really cool thing about Uranus if you get just the right exposure (not to high but not too low) you can just see the tilted pole area on the planet as you can see above.  Uranus pole is tilted as it orbits the Sun rolls like a rolling ball around the Sun so from our perspective when we view it the pole changes position! Very cool! There is not much to see on this distant gas planets mostly composed of Methane hence the green color (sometimes bluish green as well).

Images of Neptune:

Neptune with the 102mm Mak

Neptune with 102mm Mak and Triton far moon visible

Neptune is only upper right of image from stars on left

Closeup of Neptune from above with several moons Tritron farthest away on upper left

Closeup of Neptune and several moons closeby without Triton in view

Map that night corresponding to Stellarium with Neptune's moons 

Neptune and one of its Moons

Nice image of Neptune

Sharpened image of Neptune using Registax from above

Another Neptune sharpened image

Another sharpened image of Neptune

Neptune is much farther away and much dimmer but is still possible to image this planet and get some nice results and if you get the exposure and gain just right can get that nice blue color and some gas detail and maybe even some of its very dim moons.

Btw here are some image of Saturn and Jupiter from that night...always remember before each imaging session to use a Bhatinov mask on a star to get really good focus!!!! 

Jupiter

and Saturn

I hope you enjoyed todays blog!