This may be the clearest evening in two months...

[ocelotl]

They wete talking about the arrival to the continent of dry air and sand from the Sahara lately, so I was hoping for a clear day anytime this week. As you see, evening twilight doesn't show too much dust. So, I'm trying a couple things with the 3 incher and the unaluminized short 5 incher.

Read you later.

[yogi]

Then again, there is something to be said about haze in the sky ...

sunrise.jpg (39 KiB) Viewed 1318 times

Keep us informed about your adventures in the sky. Are those lenses the ones you made by hand?

[ocelotl]

Well, haze settled and the transparency we had went away. Visual limit dropped fast after 9 p.m to mag 3 or so. Fortunatelly seeing kept somewhat good, so I was limited to the Moon and a few doubles As of the time I'm posting this we are clouded out. I'll post what I recorder soon.

Yep, my newtonians are homemade, the only primary I didn't make is the small one, it has 78 mm in diameter, and a focal length of 750 mm. I began doing it in 1990, but somehow did'n't get polishing materials. When asking in the optics lab in the university, they helped me by sending it to León, Guanajuato, to the Centro de Investigaciones en Optica. The other I used is the one I made during thie pandemic. 126 mm diameter, 608 mm focal length. Both those blank were gifted to me by dad at the sae time... The large blank somehow was left sitting in drawer until last year. As you asked I already had ground another 5 inch blank 8 years ago, but somehow didn't get it aluminized so far. With the sudden self imposed enclosure, I realized I had enough material to refigure the blank I've ground 8 years ago and to grind another one, so I did it and posted photos on Zuckerberger's.

I'm waiting to be able to send my mirrors for aluminizing soon, when the optics shop at UNAM's Universum museum or the one at the Sociedad Astronómica de México open again, I have the intention of getting both blanks aluminized.

The idea is that the short focal length mirror will be mounted on a portable telescope intented for quick setup or travle, and the long focal length one will be in an older style mount that is going to be motorized for photographic and visual use.

[yogi]

Ever since I learned about your talents with optics I have been impressed by what you are doing. Lens grinding must take a very long time to accomplish and making more than one telescope is truly an amazing accomplishment. It's a shame that the atmosphere in your part of the world does not allow you to do any deep space observations. Magnitude 3 objects can be interesting, but there is so much more that your equipment is capable of resolving. The skies around here become clear from time to time, but the pollution from the city lights is probably just as bad as the haze you have over there. Then again, from a photographic point of view, haze is not all that bad as my photo shows. We too get that sand from African deserts but I do not think that is what I'm seeing in my picture. It's simply been very humid and wet lately which is ironic because many of the states to our west are going through a terrible drought.

[Kellemora]

All I can say is AWESOME there Ocelot, AWESOME!

[ocelotl]

I came to realize thet the three of us, you Gary, you Denis, and me, are under the influence of mostly the same weather patterns owing to the fact that we are in the Gulf of Mexico basin, you on the Missisipi river basin and me in the Panuco river basin. Most of our winds and humidity come from the North Atlantic Equatorial current, before transforming to the Gulf Stream. In your case, the Rockies make the winds and humidity turn north and disperse through all the US midwest, and here it all climbs the mountains up to the point where condensation permits...

Light pollution wise, Online maps show we are at similar levels in O'Fallon, Knoxville and Tlalnepantla. It may be I'm remembering how it all was easier when I was learning most of the astro stuff in the late '80s and '90s, and am just complaining.

[yogi]

I thought the South Pacific was the source of much of the weather we see in North America. Lately that part of the ocean has been over heating. The jet stream apparently has changed a bit too and forces that hot Pacific air up the west coast all the way into the Arctic. From there the flow heads south to the midwestern part of the country where the cooler air from the north meets with the warmer air from the south. The result is a lot of rain in the middle and record breaking dry heat in the west. I think you are right to say much of Mexico's weather is due to the prevailing equatorial winds, El Niño?. The jet stream loses it's punch by the time it gets near the equator, but as you say there are local sources of humidity.

[ocelotl]

It mixes all, but the humidity from the South Pacific has to overcome the Continental Divide, the easiest for it to the Gulf of Mexico is over the Tehuantepec ithsmus, that is just 200 km wide and up to 250 or so meters asl. Over here at the confluence of the Sierras Madre and the Neovolcanic axis the Pacific current overcomes the North Equatorial Atlantic current that brings humidity up here from late March until the air is warm enough from July or August until October, in average years. Last year was a dry one in mexican highlands, and this one so far hasn't been excesively humid.

[yogi]

Here in America the weather has traditionally traveled from west to east. A high altitude Jet Stream followed that pattern for many years. The polar vortex and the Gulf Stream winds did mix with the Jet Stream at times, but it all was outside our band of middle land weather. But things have changed over the last decade or two. Now the Jet Stream is not as predictable nor does it consistently flow from west to east. It diverts to a northern path west of the Rockies and comes back down about the middle of our country. Strange as it seems, this sine wave pattern has the effect of mixing that Golf Stream with Arctic air. I don't know if that will be the dominant pattern going into the future, and I can't say how much the prevailing westerlies at the equator are being affected. I do know that I am currently in the middle of it all. The weather is more intense because of the extremes in air flow that are now mixing and have not done so in the past. But we also have our share of typical weather. It's just not typical as often as it used to be.

[ocelotl]

Ocassionally the Jet Stream drifts south to this latitude, Maybe an late december or early January, as in this Valley the winds flow mainly from the Northwest along the Continental Divide or from the Northeast from the only non mountanous way from the Gulf. I've looked temperature patterns and the typical temperature ranges are similar, we just have more marked dry/wet seasons in the Central Mexican Highlands, daily range is larger due to height, and yearly range is shorter since we are nearer the Equator.

I was rememmbering, and have to correct myself. Humidity in the US and South Canada also enters from the Pacific through the Northwest Passage, between the 42 degree north latitude and the 50 degree north latitude lines. That's what you are refering to, also we have to include the worldwide convection belts, humidity evaporating and rising through the upper atmosphere around the 28 degree north latitude line, and condensing and raining near the equator and roughly at the 45 degree north line. The main jet stream flows in the middle of the temperate north convection belt, drifting with the seasons as you said...

[yogi]

When I lived in Chicago the winters always contained a few "Alberta Clippers." This was a stream of cold air aimed at Chicago and coming from the Canadian province of Alberta, thus the name. It was typically fast moving but always much colder than the already frigid Chicago weather. I believe the source of the Alberta Clippers was somewhere in Siberia. The air associated with this flow was dry but often was accompanied by dangerous wind chill factors. The west-to-east weather pattern of air with more humidity did not apply in these instances. I don't know how far south the Alberta Clippers traveled, but I've never heard the term here in Missouri during the last five years that I lived here. It's just cold air from Canada. LOL

[ocelotl]

I was forgetting to deliver. This is a test, I took a small 640 x 480 resolution 30 fps video at around 8 p.m. that totalled 1333 frames using a point and shoot camera (Canon PowerShot A710IS) at 4.6X optical zoom, on afocal mode, using a 25 mm Orthoscopic made in León Guanajuato by the Centro de Investigación en Óptica, meaning 24.32X on the telescope and 112x total. Then I processed the video using RegiStax, using the best 710 frames.

I'm uploading the result image and one where I enhanced a bit the detail contrast. Again, this is by no mean the best possible, just a quick and dirty first try with a low res camera.

[yogi]

Your photos are magnificent, even if you insist they are not the best. Having said that, I am a little surprised that 112x magnification does not produce more crater detail. Regardless, 1/30th of a second exposure time is a lot faster than I thought was possible in order to capture any detail. Apparently the lunar surface is a lot more brilliant than I thought.,

[Kellemora]

Great Photo's there Ocelot!

[ocelotl]

It's a relative masuremant, anyway. Effective focal length would be 650 mm. The insistence is because the image is not a prime focus one, neither was taken with a DSLR. Using the full possible optical zoom of the camera and a 9 mm eyepiece a 2,350 mm effective focal length is possible, also waiting for twilight to darken would bring more contrast and better detail.

[yogi]

I don't know a lot of the technical details of photography but I do know that focal length determines the angle of view. At 2.35 meters that angle has to be very narrow and you probably could not fit the entire moon into a single view. You would, however, be able to get some extraordinary photos of individual craters in that case. You are doing some amazing things there, Juan.

[ocelotl]

According to the manufacturer, this Point and Shot has a sensor of 5.75 mm x 4.32 mm. A Canon EOS Rebel XS (The model of my DSLR) has a sensor of 22.2 mm x 14.8 mm. Will check with the DSLR next clear evening.

[yogi]

I'm certain the camera's sensor pixel count has a major influence on the resolution of any given frame. The part I'm unclear about is the field of view which is determined by the focal length and the size of the lens. At 2.35 meters that angle would be less than one degree of arc for smaller lenses, the kind I'd expect to see in your telescope. The moon (and sun) take up about one full degree of arc in the sky so that any field of view less than that would miss part of the object. Your lunar images clearly show the entire sphere of the moon.

[ocelotl]

I was checking some tests I did previously and I found this from May 18th. Thought it would be good to show it to you. It came from my DSLR, Canon Rebel XS. It's a 50% size rescalled copy. I think it was taken with the unaluminized 126 mm diameter, 608 mm focal length tempered soda lime glass blank with my Meade # 126 Barlow lens. ISO 1600, 1/8 seconds. The rescale was done with Photoshop portable CS6. No additional processing was done.

[ocelotl]

This is other image I took with the DSLR, Canon Rebel XS, on August 10th. This time at prime focus and with the unaluminized 126mm diameter, 882 mm focal length blank I bought 8 years ago from Firsthand Discovery. I left that piece of glass idle without figuring it until this year...

Heat blur and the lack of a precise focus is apreciable here. Under good conditions, the yellow ID plates on the Tower should be readable. I liked the contrast with the background caused by a cloud in the right place. Contrast may need an enhance, but apart of the rotating and rescaling, no processing was done here.

ISO 1600, 1/200 s.