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Re: How to use a planetary camera for occultations

 

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Hi Graem

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The LED is flashed into the optical path at the beginning and end of the observation.

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You can use the flashes to work out the capture delay of your camera system and the offset of your PC clock. However, you will need to have the PC clock as close the accurate as possible, using either NTP or GPS to sync the PC clock to better than one second.

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The flashes can also help you work out if there is any jitter in the time interval between captures.

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BTW, you will find USB GPS dongles on eBay with a 1PPS flash if you don¡¯t want to go DIY. Just use a USB extension lead to connect the dongle to your PC, and make up a clip to attach it to the front of your telescope. You could then use the GPS dongle to correct your PC clock.

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Cheers,

Steve.

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From: [email protected] <[email protected]> On Behalf Of Graem Schmidt
Sent: Tuesday, November 28, 2023 5:47 AM
To: [email protected]
Subject: Re: [OccultWatcher] How to use a planetary camera for occultations

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Hello: I am not clear on one point - are you planning to shine the LED from the GPS module into the telescope with no gating (I.e. it could flash while the occultation is in progress?)?

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Graem

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-------- Original message --------

From: jerryrst <jroyston@...>

Date: 2023-11-27 9:23 a.m. (GMT-07:00)

Subject: Re: [OccultWatcher] How to use a planetary camera for occultations

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Hello all,
??? I used a module with antenna. One can also attach an aerial. It has an LED wish flashes with the PPS, albeit not very bright.
It has a PPS output on one of the pins, you could add an FET, resistor and LED to produce a brighter flash
If the signal is weak you can attach an external GPS aerial, I have one on a 5m cable
See for a suitable module
Best wishes,

Jerry


Am 27.11.2023 um 12:40 schrieb smrussellau via groups.io:

Hi all

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Thanks for the interesting discussion.

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Another source of 1PPS flashes are GPS dongles such as the Ublox7 et al. Cheap off the self solutions.

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These should work with software such as NMEATime2 to bring the PC clock well within the <1sec accuracy required to know which seconds the flashes correspond to while using capture software that uses the PC clock for timestamps. All you need is a USB extension lead to use the dongle as both a flasher and a ?time source. No need for Internet for NTP.

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Steve P, I hope to find the time to test this out prior to the next TTSO.

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Cheers,

Steve R.

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