On Thu, Feb 9, 2012 at 8:28 AM, Siegfried Jachmann <siegfried@jachmann.org>wrote:

They have star shows. They have a newdigistar projector. It's no better than the old digistar. We took the grandkids and I was again thoroughly disappointed in the quality of the star images. Bright stars are big blobs, Jupiter looked like a big nebula, the narator made several mistakes, i.e., did you know the Milky Way has 300 "trillion" stars in it. The operators struggled through the program. Purists will be disapointed.

There's no excuse for untrained operators. Could the imaging shortcomings be solved with software fixes?

All planetarium projectors have their strong points and their weak points.  During the development of Digistar we were able to increase brightness and reduce image size considerable, but we were never able to achieve the pinpoint sars produced by Spitz planetarium projectors.  Zeiss projectors produce a nice star field, but the images are significantly larger than Spitz stars.  Digistar images are larger than Zeiss stars.  Digistar offers significantly more flexibility than the others, and allows 3D travel, proper motion demonstrations, and rastered images.  The others do not.  Planetary position accuracy is also better with Digistar.   From what I have seen of the new Digistar, the bright stars are actually many pixels in size.This is an attempt to simulate higher brightness, but it doesn't work well for me.  Others have made similar comments as well.    Brightness in the original digistar was limited by the amount of energy you could put into a phosphor and still have a linear response.  At a certain level, you can pump more energy into the phosphor, but local heating and other effects will cause the brightness to peak, and then slightly decrease.  This is my biggest dissapointment in our original plan.  As I mentioned, we dramatically improved the image from when we first started, but it still need even more.  The latest Digistar gets mor light by making the stars bigger.   To a certain extent, the real stars do look bigger as their brightness increases, but not as much as Digistar represents.  Even the Zeiss machines show larger images for brighter stars, but not as much as Digistar.   So, Chuck, the bottom line is that software changes wil not really solve the problem.  It is a hardware limitation.  There are some algorithms we tried and had some success with, but the basic problem is trying to get a larger number of photons out of a projection CRT.    Yes, we contemplated lasers too, but the problems of deflecting the beam at sufficient angls and at a speed required to image 6713 stars (the number of stars brighter than magnitude 6.5 in the Yale Catalog of Bright Stars) were even greater than the ones faced by using projection CRTs.  We would have had to limit the number of stars to around 2000 and perhaps a 60 degree field of veiw.  There were also speckle and color issues to deal with.   That's probably more than you've ever wanted to know.  I hope you were able to find your answer in there somewhere. ________________________________ From: Siegfried Jachmann <siegfried@jachmann.org> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Thursday, February 9, 2012 10:04 AM Subject: Re: [Utah-astronomy] Clark Planetarium Old "Jake" had a much better star field. That would be a Brent question but I think in order to get brighter, i.e., Jupiter, they have to go to a bigger image. On Thu, Feb 9, 2012 at 9:31 AM, Chuck Hards <chuck.hards@gmail.com> wrote:

On Thu, Feb 9, 2012 at 8:28 AM, Siegfried Jachmann <siegfried@jachmann.org>wrote:

...

They have star shows. They have a newdigistar projector. It's no better than the old digistar. We took the grandkids and I was again thoroughly disappointed in the quality of the star images. Bright stars are big blobs, Jupiter looked like a big nebula, the narator made several mistakes, i.e., did you know the Milky Way has 300 "trillion" stars in it. The operators struggled through the program. Purists will be disapointed.

There's no excuse for untrained operators.  Could the imaging shortcomings be solved with software fixes? _______________________________________________

TO FUNNY Mark   Mark Shelton Indian Hill Middle School Tech Ed. Teacher Salt Lake Astronomical Society Board Member (School and Special Star Parties Coordinator)  ________________________________ From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Thursday, February 9, 2012 1:34 PM Subject: Re: [Utah-astronomy] Clark Planetarium On Thu, Feb 9, 2012 at 10:04 AM, Siegfried Jachmann <siegfried@jachmann.org>wrote:

Old "Jake" had a much better star field.

Here's a few photos of years gone by: http://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/USHS_Class&CISOPT... http://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/USHS_Class&CISOPT... http://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/USHS_Class&CISOPT... http://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/USHS_Class&CISOPT... And here's a photo of the planetarium when Patrick started working there. That's his car parked right in front. ;-) http://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/USHS_Shipler&CISO... _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".

On 09 Feb 2012, at 13:34, Chuck Hards wrote:

Here's a few photos of years gone by:

http://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/USHS_Class&CISOPT... http://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/USHS_Class&CISOPT... http://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/USHS_Class&CISOPT... http://content.lib.utah.edu/cdm4/item_viewer.php?CISOROOT=/USHS_Class&CISOPT...

Oh wow, I must be old. I actually remember using parts of the console shown in the second image (it had been updated a bit by the time I started at Hansen in 1975). Of course I remember Jake. Thought, with it's occasional mechanical breakdowns I also remember it being called "Jerk".

And here's a photo of the planetarium when Patrick started working there. That's his car parked right in front. ;-)

Ha. You got me on that one. Grins! patrick

Computer glitches continue to plague even modern, high-tech productions. Digital, modern shows are not superior to those of decades past. They may be more hands-off, but their real allure is that they are less labor-intensive than shows of old. Labor is ALWAYS the greatest expense in any business venture. The bean-counters rule even our educational efforts. Modern society sucks. Q.E.D. On Feb 9, 2012 7:20 PM, "Patrick Wiggins" <paw@wirelessbeehive.com> wrote:

Like you Chuck, I've not been to the new place so I can't speak to that but regarding the "star shows" even by the time I was shown the door a year or so before Hansen closed, live "Star IDs" as some of us called them were becoming less frequent being replaced by canned (recorded) shows where the operator did little more than welcome the audience and push the "start" button.

Happily I was abe to get the shop to install a hand paddle in "the pit" in the center of the room (from which Jake used to rise and in which the Digistar project sat in later years). Using that I and a few other likeminded presenters were still able to do mostly manual shows and really get involved with the audience, answering questions on the fly and sharing the occasional laugh instead of crouching behind the console in the back of the star chamber (later renamed "star theatre").

But, let's face it, automation allows the possibility of doing so much more in a full blown production. So I see where it has it's place. But I still miss interacting with the audience in live star IDs. Fortunately I still get to do it at star parties.

patrick

On 09 Feb 2012, at 08:15, Chuck Hards wrote:

...

Does anyone know if the planetarium has actual "star shows", like Hansen used to have? Constellation identification, graphic demonstrations of planetary movement, seasonal changes, etc.? Like in the "good old days"?

I loved those star shows.

"And may we at Hansen Planetarium be the first to wish you 'Good Morning'." ;-)

I really couldn't see anything resembling a "star show" on the Clark website. Everything seems to be "movies".

I have to admit that I have yet to set foot in Clark. I tend to avoid downtown SLC and have only been in the city a handful of times in the last 20 years. There just never seems to be free time available during hours when places are open, anyway.

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