C/2006 P1 McNaught is currently passing close to the Sun. At a mere 18 million miles (0.197 AU) from the Sun the intense solar radiation is causing the comet to boil and vent violently. The resulting cloud of gas and dust is reflecting enough sunlight to brighten the comet dramatically. Estimates are placing the comet at mag. -5 or even mag. -6. This is much brighter than even Venus! Some observers are reporting easy unaided eye visibility, but in the sky over Tucson a lot of dust and aerosols in the air are causing a great deal of glare around the Sun. Thus binoculars or a telescope is required to see the comet.
C/2006 P1 McNaught captured with a TV-76 operating at f/5 and a Canon 20Da DSLR, 1/8000 sec, gain at 100ISO. Taken 2:29pm 14 Jan, 2007 and processed with Photoshop. Three frames aligned and stacked in Photoshop to improve the signal to noise ratio.The challenge is that Comet McNaught is just five degrees east of the Sun. Observing so close to the Sun presents distinct dangers, I do not want to fry my retina! So I carefully positioned my TV-76 on the alt-az mount so that the Sun was just behind the edge of my carport. Thus I could pan around and locate the comet with little fear of direct sunlight down the tube. A few frames with the Canon 20Da turned out OK but not great, those dust and aerosols in the sky and the resulting glare is reducing the signal to noise in the images. The photo to the right is a stack of three images in an attempt to improve the signal to noise, then greatly cropped in and levels adjusted in Photoshop.
The view was better in the eyepiece. A sharp point of the coma with a fan shaped tail. This really looks like a classic comet, I had not expected such a good tail in the bright sunlit sky. This is my first daytime comet, and since the opportunity may not come again anytime soon, this may be my only chance to see one, truly a once in a lifetime event!
About a dozen times a century Mercury passes in front of the Sun as seen from Earth. The event is observable with a modest telescope and a solar filter, Mercury can be seen as a small black dot crossing the surface of the Sun. If half of those happen when the sun is below your horizon the average person will have the chance to observe five or six in a lifetime. Since the next opportunity will not occur until May 9th, 2016 I didn’t want to miss this one!
90mm refractor Violet Haze photographing the transitI took the day off.
Considering that Mercury never gets very far from the Sun means that most of the time you can observe Mercury it is low on the horizon and is typically seen through a great deal of atmospheric distortion. A transit is one exception to this, during a transit mercury is a sharp disk, very different from the multicolor jello ball that is usually seen.
The 2006 Transit was well timed for observation across western North America, starting just after noontime and ending at 5:09pm MST. This put the Sun high in the sky for all but the last part of the event. Our weather cooperated as well, delivering a cloudless blue sky the entire day in place of the clouds that had been forecast. The air was reasonably steady as well allowing good photographic and observing conditions.
I took advantage of the weather and photographed almost the entire transit, all but the very end when the sun sank below the trees in my neighborhood. I used the Canon 20Da and setup a timer to shoot every 5min. The only issue was the inability to do a polar alignment on the mount when setting up in the middle of the day. The result was I had to manually guide the scope every 10-15 min to keep the sun centered.
I got plenty of good photographic material, enough for a few single photos as well as an animation of the transit. A transit is an impressive demonstration of the scale and arrangement of our solar system. Not hard to visualize the reality of those textbook drawings of planetary orbits after you have had such an opportunity to see the real thing.
No complaints on my second Mercury transit.
The Mercury transit of 8 Nov 2006 in progress. Mercury is about halfway between the center to the bottom, a large sunspot complex is visible on the left edge. Photo with a 90mm APO refractor, a Thousand Oaks full aperture filter and a Canon 20Da camera.
Digital SLR cameras make surprisingly good astrophotography cameras on bright objects. Good sensitivity, low noise and a convenient form factor make these camera a good choice for shooting the night sky.
One useful modification to the camera is removing the standard IR cutoff filter present in cameras and replacing it with a filter that is tuned to let in more of the red. The new filter should allow light at 656nm, what astronomers call hydrogen alpha, or Hα, the light emitted by neutral hydrogen atoms, the most common element in our universe. This is the red glow that makes the emission nebulae so colorful. An astrophotographer can do the filter change themselves, send it to a specialist who can do the work, or buy an already “modded” camera. Canon has produced two special models specifically for the astrophotography market, the EOS 20Da and 60Da, with this special filter.
Below, one can see the results of using modified, and unmodified cameras and relatively small telescopes…
M16 and M17, the Eagle Nebula and Swan Nebula, single 8 minute exposure at ISO 800, Canon 20Da DSLR camera mounted on a Televue-76 APO telescope with a 0.8x focal reducer/field flattener
Baade’s Window, single 8 minute exposure at ISO 800, Canon 20Da DSLR camera mounted on a Televue-76 APO telescope with a 0.8x focal reducer/field flattener
The Andromeda Galaxy, M31, single 8 minute exposure at ISO 800, Canon 20Da DSLR camera mounted on a Televue-76 APO telescope with a 0.8x focal reducer/field flattener
The Lagoon Nebula and The Trifid Nebula, single 8 minute exposure at ISO 800, Canon 20Da DSLR camera mounted on a Televue-76 APO telescope with a 0.8x focal reducer/field flattener
Omega Centauri, NGC5139, single 2 minute exposure at ISO 800, Canon 20Da DSLR camera mounted on a Televue-76 APO telescope with a 0.8x focal reducer/field flattener
B72, the Snake Nebula, single 8 minute exposure at ISO 800, Canon 20Da DSLR camera mounted on a Televue-76 APO telescope with a 0.8x focal reducer/field flattener
A total lunar eclipse on the night of August 27-28, 2007 with the Moon deep in the Earth’s inner shadow. A dark eclipse, this exposure shows a number of stars surrounding the Moon
