Search our FAQ for answers to anything you might ask.


In order to task Alnitak telescopes, you need to create an imaging plan in the Plans menu once you are logged into the system. We provide graphical user interface that allows you to create plan files easily by selecting your astronomical target by name or coordinates and specifying the number of images, filters and other options. Once the plan is created, you will need to reserve the observation time slot in the Telescope Reservation menu by clicking and dragging across the time slots and assign your imaging plan to a range of time slots. Once the reservation is processed successfully your images and log files will appear for downloading in the Data Files menu.

Once Alnitak telescope has finished executing your imaging plan, your images will be available for downloading via Alnitak web interface in the Data Files menu in the FITS format. You can also download your files in bulk via FTP connection to portal.alnitakobs.com (port 21) using your Alnitak account e-mail and password as login credentials.

Yes, we will provide fully calibrated FITS files with bias, dark and flat-frame calibration applied automatically by the system. Raw images will also be available in the RAW folder along with the calibrated images.

You can reserve any time up to 15 minutes in advance.

The total length of your reservation should cover your expected imaging time along with the additional technical overhead time required for slewing, auto-focusing, autoguider initialization and other tasks. The amount of overhead depends strongly on the chosen exposure duration and auto-focusing intervals, but generally for most long-exposure imaging tasks it is approximately 1.2 to 1.5 times the imaging time. For example, for a plan with a total of 100 minutes of expected imaging time, reserve a time slot of approximately 120-150 minutes. For very short exposures or plans with very low total number of frames the overhead time may increase dramatically.

If there is no reservation following your reserved time slot then your plan will continue to run until the roof is closed or another reservation is encountered on the same night. If there is a reservation that follows yours, then your plan will be aborted by the end of your reserved time slot.

Advanced Features

In addition to the selection of target, filter and exposure duration, Alnitak imaging plans allow to customize pattern repetition, refocusing behavior, dithering, photometric defocusing, binning modes and other features.

Please refer to Creating Custom Plans page for the full description of telescope control directives and target specifications.

Yes, you can mix all filters in the same plan. The A1 telescope has four parfocal filter groups:

  • Broadband LRGB
  • Narrowband H-alpha, [O III] and [S II]
  • Johnson/Bessell Photometric UBVRI
  • Empty slot (no filtering)

Alnitak A1 will focus on each filter change and will use the actual imaging filter selected for focusing.

Billing & Support

If the observatory roof is closed due to the weather, you will not be billed for any reservation time and will be able to reserve time on another night for your imaging plans.

We provide full satisfaction guarantee. We will issue full refund if the data has arrived poorly calibrated or with defects due to poor tracking, equipment malfunction or any other reason. The refund claim can be submitted online via the Technical Support menu and is usually processed within 24 hours. Please note that guiding may not be optimal for targets with elevation below 40°.

All reservations consist of one or multiple 15-minute time slots. Each 15-minute slot is billed with a discount based on the observed Moon illumination at the beginning of the slot. The discount is provided in the Pricing page.


The exposure duration would directly depend on the uncertainty you need to achieve. The AAVSO Guide to Photometric Uncertainty is a good source of information on the relationship between the signal-to-noise ratio (SNR) and photometric uncertainty.

As the first first approximation the (1/SNR) formula can give a good indication on the SNR required, e.g. SNR=100 would yield roughly a 0.01 mag uncertainty. Depending on the uncertainty you require for your project,you can then use various SNR calculators to estimate how long the exposure should be for your target, e.g. Michael Richmond’s Signal-to-noise calculator for CCD photometry.

It is always best to experiment with a series of exposure durations around the estimated value in order to make sure you are not oversaturating the sensor with too long of an exposure and stay within the linear regime. Please refer to the specifications of the telescope for the pixel scale, sensor read noise, linear capabilities of the camera and other data on the A1 system.