STScI Logo

Hubble Space Telescope
Late Breaking News

Changes since the Cycle 23 Call for Proposals has been Frozen

February 13, 2015

APT 23.0.1 Released for Phase I Use

Dear Colleagues,

The Space Telescope Science Institute is pleased to announce the release of APT 23.0.1 and its associated documentation. This is the version of APT that needs to be used to support HST Cycle 23 Phase I submissions.

The Cycle 23 Call for Proposals and Science Justification Templates can be found on the Cycle 23 announcement website at:

Please remember the HST Cycle 23 Phase I Deadline is 8:00pm EDT on April 10, 2015.

APT can be downloaded from our APT website at:


The procedures for verifying APT submissions are the same as from Cycle 21 & 22. You will continue to see a message verifying a successful submission in the Submission Log on the Submission Screen in APT. With the current procedure, the PI and all CoIs will receive an automatic e-mail acknowledgement that the merged PDF submission was received successfully after the Submission Log is updated and the Phase I Submission Server processes the submission. ONLY after the Phase I deadline has passed, and all submissions are in their final form, will the PI and CoIs receive final notification that their submission has been successfully processed; this e-mail will mark the completion of that submission.

The Roadmap contains links to short training movies, and to the relevant sections of the documentation, on the basics of using APT (the GUI interface and entering information) and on analyzing the scheduling constraints of your observations..

January 07, 2015

No News is Good News

At this time there is nothing new to report.

DD Time

Up to 10% of the available HST observing time may be reserved for Director's Discretionary (DD) allocation.

Mid-Cycle Proposals

Up to 200 orbits per cycle will be available for Mid-Cycle GO programs. Mid-Cycle programs were initiated in Cycle 23 to provide the community with an opportunity to propose for in-cycle observations of recently-discovered, non-variable objects. As such, they complement Director’s Discretionary programs, which target unexpected transient phenomena and time-critical observations..


Scheduling Considerations