APOD: Antares Rocket Launch (2013 Sep 21)

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Expand view Topic review: APOD: Antares Rocket Launch (2013 Sep 21)

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by neufer » Mon Sep 23, 2013 1:07 am

http://en.wikipedia.org/wiki/Rocket_engine#Plume_physics wrote:
<<Rocket plume varies depending on the rocket engine, design altitude, altitude, thrust and other factors.

Carbon rich exhausts from kerosene fuels are often orange in color due to the black body radiation of the unburned particles, in addition to the blue Swan bands. Peroxide oxidiser based rockets and hydrogen rocket plumes contain largely steam and are nearly invisible to the naked eye but shine brightly in the ultraviolet and infrared. Plumes from solid rockets can be highly visible as the propellant frequently contains metals such as elemental aluminium which burns with an orange-white flame and adds energy to the combustion process.

Some exhausts, notably alcohol fueled rockets, can show visible shock diamonds. These are due to cyclic variations in the plume pressure relative to ambient creating shock waves that form 'Mach disks'.

The shape of the plume varies from the design altitude, at high altitude all rockets are grossly under-expanded, and a quite small percentage of exhaust gases actually end up expanding forwards.>>

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Beyond » Sun Sep 22, 2013 11:52 pm

Maybe part of it is the fuel that's used :?:

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Nitpicker » Sun Sep 22, 2013 11:40 pm

Case, I don't know for sure, but I am going to make an educated guess that it is due to different atmospheric conditions. Different temperature, pressure and humidity, most likely. I'll stand to be corrected. Interesting question.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Case » Sun Sep 22, 2013 11:30 pm

APOD Robot wrote:Image
Some launches, like this APOD, show the rocket detached from the plume, while many others show the plume from the rocket all the way down. Why is that?
Image

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Nitpicker » Sun Sep 22, 2013 11:04 pm

Chris, I think I would be foolish to ignore your advice. You appear to have the experience to back you up. Thanks.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Chris Peterson » Sun Sep 22, 2013 2:55 pm

Nitpicker wrote:Thanks Anthony and geckzilla, but I think writing all this down has helped me to figure out what I really want. Whilst IR-range photography would be amazing for some things, unless it was a relatively simple switchover, I would say no. The Canon 60Da seems to be always sensitive to IR, which is not quite what I'm looking for.

I think the 1:1 pixel res for recording movies is more important to me. Without buying a whole new DSLR, maybe a smallish, cheapish tablet PC connected to a goodish webcam is what I should be looking for, whenever I want a narrower field and slower focal ratio. I could connect the tablet to the D5100 DSLR too, for wider field stuff. I'm sure the tablet screen would be better than the smallish live-view screen on the DSLR.

Tis not that important, as I only have a modest scope and I would rarely venture into really dark skies. Having said that, I'm still amazed at what I can see from my little suburb on the fringe of town. Damn fine hobby!
Not what you're asking for, but I'll say it nevertheless. For high resolution planetary imaging, use a good digital video camera and take your laptop. It adds very little complexity, and gives you access to much higher quality equipment and much more flexible image. It's worth the trouble.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Nitpicker » Sun Sep 22, 2013 10:05 am

Thanks Anthony and geckzilla, but I think writing all this down has helped me to figure out what I really want. Whilst IR-range photography would be amazing for some things, unless it was a relatively simple switchover, I would say no. The Canon 60Da seems to be always sensitive to IR, which is not quite what I'm looking for.

I think the 1:1 pixel res for recording movies is more important to me. Without buying a whole new DSLR, maybe a smallish, cheapish tablet PC connected to a goodish webcam is what I should be looking for, whenever I want a narrower field and slower focal ratio. I could connect the tablet to the D5100 DSLR too, for wider field stuff. I'm sure the tablet screen would be better than the smallish live-view screen on the DSLR.

Tis not that important, as I only have a modest scope and I would rarely venture into really dark skies. Having said that, I'm still amazed at what I can see from my little suburb on the fringe of town. Damn fine hobby!

Thanks for reading. I probably should have made these queries in another part of the forum.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by geckzilla » Sun Sep 22, 2013 2:37 am

Nitpicker wrote:To be honest, even if I did buy myself a nice new DSLR, I'd be reluctant to remove the IR filter, as it sounds like the process is irreversible, or practically so.
The "a" in 60Da seems to stand for astronomy. You should check the link. :wink:

Edit - may have misunderstood what you meant, though.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Nitpicker » Sun Sep 22, 2013 2:26 am

To be honest, even if I did buy myself a nice new DSLR, I'd be reluctant to remove the IR filter, as it sounds like the process is irreversible, or practically so. I'd prefer it as a toggle at the push of a button, thanks very much. Am I being too demanding? (Based on neufer's post re seeing through clothing, it could be called "pervert mode", to serve as a warning to the innocent user.)

My wife's Nikon D5100 is a great camera, especially at high ISO. The 23x15mm sensor is really well suited to my 1500mm focal-length, f/10 alt-az goto SCT. It is the perfect match to frame the whole moon in a single exposure at impressive resolution ... as well as so many of the brighter deep sky thingies, with single exposures of no more than 30 seconds.

Because I spend a lot of time in front of a computer in the daytime, I'd rather spend my nights outside under the stars (in my comfortable suburban backyard), than inside stacking frames. As such, I've really come to appreciate the noise from my high ISO (3200 - 10000) deep sky images, and I try to push them to the limit of my sky glow as fast as possible. (There is also a limit to the tracking accuracy of a small, unguided alt-az mount, but mine is impressive enough for me.)

The one thing lacking from the D5100 (apart from magic IR filter toggle) is the ability to record movies at 1:1 pixel resolution (which many Canons appear to have). The D5100 can only use all 16 mega pixels (rather than a small portion of the sensor) to record HD videos, meaning that the resolution is down-sampled by about a factor of 5. This makes it not very good for imaging the planets, which dashed my hopes somewhat. Thus far (and I've only been doing it for less than a year) I've become rather the expert at taking blurry shots of the planets.

If anyone has any affordable solutions for recording movies at 1:1 pixel resolution, which does not require taking a laptop/tablet into the field, I'd be interested to hear. The range of DSLRs on the market is frankly too baffling for me, and all the people employed to market them should take a good look at themselves. (I'd also like to avoid a dedicated astro-camera if possible, as that will tempt me to buy a bigger telescope ... then an observatory ... and I might miss my family.)

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by geckzilla » Sun Sep 22, 2013 1:02 am

Anthony Barreiro wrote:
Nitpicker wrote:Congratulations. Beautiful. Sublime.

Makes me want to go out and get laser eye surgery, to see in infra red. (Radio waves might be cool too, when I'm in the mood.)

I'd really love to remove the IR filter on the DSLR I use, but it belongs to my wife and she would kill me. She loves the visible spectrum. One might say we don't see eye to eye on this topic.
Get a Canon 60Da.
For the low, low price of only $1500 USD! Wish I could justify such a purchase other than wanting to nerd out on special features.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Anthony Barreiro » Sun Sep 22, 2013 12:55 am

Nitpicker wrote:Congratulations. Beautiful. Sublime.

Makes me want to go out and get laser eye surgery, to see in infra red. (Radio waves might be cool too, when I'm in the mood.)

I'd really love to remove the IR filter on the DSLR I use, but it belongs to my wife and she would kill me. She loves the visible spectrum. One might say we don't see eye to eye on this topic.
Get a Canon 60Da. A reviewer in Sky and Telescope compared the warm daytime color balance to Kodachrome film.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Colorblind » Sat Sep 21, 2013 6:28 pm

Looks like a beautiful, normal picture to me. I'm blue/grey and red / green colorblind. Can’t tell if the grass or the water is not a normal color. Sky looks a little dark, that’s about it.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Joe Stieber » Sat Sep 21, 2013 1:16 pm

Unfortunately, this daytime launch of the Antares rocket was essentially invisible to those of us in southern New Jersey (roughly 100 to 150 miles north of Wallops Island, VA). Despite a beautiful, clear blue sky, I saw nothing from the NJ suburbs of Philadelphia, PA, and neither did a number of other observers in the region. This was in sharp contrast to the nighttime launch of the Minotaur V carrying the LADEE spacecraft out of Wallops on September 6, 2013, which provided a spectacular view of the rocket plume and smoke trail to many folks in NJ and surrounding states. I'm hoping that some of the future Antares launches will be at night.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by neufer » Sat Sep 21, 2013 12:43 pm

Nitpicker wrote:
Congratulations. Beautiful. Sublime.

Makes me want to go out and get laser eye surgery, to see in infra red. (Radio waves might be cool too, when I'm in the mood.)

I'd really love to remove the IR filter on the DSLR I use, but it belongs to my wife and she would kill me. She loves the visible spectrum. One might say we don't see eye to eye on this topic.
http://en.wikipedia.org/wiki/Infrared_photography#Digital_cameras wrote:
<<Digital camera sensors are inherently sensitive to infrared light, which would interfere with the normal photography by confusing the autofocus calculations or softening the image (because infrared light is focused differently from visible light), or oversaturating the red channel. Also, some clothing is transparent in the infrared, leading to unintended (at least to the manufacturer) uses of video cameras.Thus, to improve image quality and protect privacy, many digital cameras employ infrared blockers.>>

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Beyond » Sat Sep 21, 2013 11:38 am

Nitpicker wrote:Congratulations. Beautiful. Sublime.

Makes me want to go out and get laser eye surgery, to see in infra red. (Radio waves might be cool too, when I'm in the mood.)

I'd really love to remove the IR filter on the DSLR I use, but it belongs to my wife and she would kill me. She loves the visible spectrum. One might say we don't see eye to eye on this topic.
No problem... save up and buy another one and take the filter off.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Nitpicker » Sat Sep 21, 2013 10:59 am

Congratulations. Beautiful. Sublime.

Makes me want to go out and get laser eye surgery, to see in infra red. (Radio waves might be cool too, when I'm in the mood.)

I'd really love to remove the IR filter on the DSLR I use, but it belongs to my wife and she would kill me. She loves the visible spectrum. One might say we don't see eye to eye on this topic.

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Boomer12k » Sat Sep 21, 2013 8:32 am

Go, baby, Go!

:---[===] *

Re: APOD: Antares Rocket Launch (2013 Sep 21)

by Beyond » Sat Sep 21, 2013 4:35 am

A cloud (cough-cough) of smoke and a hardy (cough-cough) YEE-HAA :!: We have lift-off. The Oreos, and other things, are on the way. :yes:

APOD: Antares Rocket Launch (2013 Sep 21)

by APOD Robot » Sat Sep 21, 2013 4:06 am

Image Antares Rocket Launch

Explanation: The sky looks dark in this scene from the Mid-Atlantic Regional Spaceport (MARS) at NASA Wallops Flight Facility, Virginia. Captured on Wednesday, September 18, an Orbital Sciences Corporation Antares rocket is leaving launch pad-0A with the Cygnus cargo spacecraft aboard. Though it looks like night, the photograph was taken at 10:58am EDT, under bright, clear morning skies, with a digital camera modified to record infrared images. The Sun itself is above and left of the picture frame, creating strong glare and internal reflections in the camera lens at near-infrared wavelengths. In the false-color presentation, the vegetation and watery reflections also take on an otherworldly pallor. Reaching orbit, the Cygnus spacecraft is now on its way to a Sunday rendezvous with the International Space Station. The spacecraft will deliver about 1,300 pounds (589 kilograms) of cargo to the Expedition 37 crew.

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