(c) Skyhound

I took this image of NGC 1535 with iTelescope T32. It is a color composite made from 2x3min exposures in the OIII and H-alpha filters. The OIII was mapped to blue and the H-alpha to red. Green was synthesized as a combination of the two. The OIII line is the stronger, thus the blue-green color.

 

The field in a six-inch at 50x. North is down and east is right.

Visually, NGC 1535 is my all-time favorite planetary nebula.  Although a fine object for small telescopes, it really shines in large aperture instruments. 

As a small, very high surface brightness object, it takes magnification extremely well.  So for the best view, it is important to use as much magnification as the conditions will permit. Make sure it is high in the sky. If the seeing is poor, come back on another night and try again. It really is worth getting a good look.

In my six-inch, this planetary is obvious at 50x.  It appears very bright.  My best view is at 270x, where it appeares as an elongated disk with a visible central star.  The image on the right closely resembles the appearance of NGC 1535 in small telescopes.

My first view of NGC 1535 in a large- aperture instrument came with the first light of my 18" Dob way back in October 1999.  At 166X it appeared little different from the view in my 6-inch. I logged the following, "Nearly round. Very bright. Fuzzy edges."

When I inserted a 2X Barlow for another look I was stunned.  Here is my log from that night and a drawing of what I saw (left):

"As it came into view I was astonished, like seldom before. "Oh my God", I said out loud to the darkness.  This was no visual observation of a planetary nebula.  It was a photograph!  Very bright, with a non-stellar appearing central "star" with sharp edges.  Some dark surrounding this, then a bright, slightly oval ring -- quite distinct.  All this embedded in a slightly oval, sparkling haze."

This is a wonderful object that I felt should have a memorable and descriptive name. I dubbed it "Cleopatra's Eye", in reference to the oblong inner ring that surrounds the central star. It is gratifying that as a result of my original post many years ago, this name has found some acceptance in the visual observing community.

Planning Your Own Observation

Many more columns are available, but we had to squeeze things to fit our space here.

The SkyTools Nightly Planner is set up above for November 24, at Del Rio Texas, with a 10-inch LX200.  Cleopatra's Eye is selected. The graphic at the top shows the darkness of the sky during the night. The red dashed line is the altitude of Cleopatra's Eye. The teal line is the altitude of the moon, which you can see sets at about 23:00 (11 PM). The green horizontal line is an altitude of 20 degrees above the horizon, below which you are looking through more than twice as much air as overhead. So you want to observe above this line. We can see that our best view will be from about 10:00 PM to 3:30 AM, when our object is highest in a dark sky, and this is reflected in the times listed in the Begin, Optimum, and End columns. These times are computed for when the contrast is maximized. Because of the high surface brightness of our target, the phase of the moon, and its separation in the sky, SkyTools calculates that we can still get a good view even when the moon is still up. The very best view will be at 12:40 AM.

Other software may do something similar, but they only make generic claims for your telescope, rather than specific calculations for an actual night under actual observing conditions, including the altitude and phase of the moon and level of light pollution. On another night, SkyTools may say that the object is difficult to see in the eyepiece rather than obvious. 

When we right-click on our object we have options: to see everything SkyTools knows about it (right), to view in it the Atlas, view/print a finder chart, slew your telescope, create/view log entries, download a DSS image, etc. The time is automatically selected to be the optimum time to view.

Click below to see a full size finder chart that was made by right-clicking on the object in the planner. 

This finder chart is for an 8-inch Dob. The left side shows the naked-eye sky with Rigel QuikFinder circles at the location of the object. On the right is the view in a wide field eyepiece. The orientation and magnitude limits are properly calculated for the time and location, including light pollution, twilight, and moonlight. As a result, it is a simple matter to find this tiny planetary. Once centered, insert a higher-power eyepiece. A version of the same chart can be printed and taken into the field.

 

Greg Crinklaw Developer of SkyTools 

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