Lead: Quanzhi Ye (University of Maryland)

Desciption: The Jupiter Trojans, or simply the Trojans, are a group of asteroids liberated around the Jupiter L4 or L5 points. They raise interesting questions surrounding their origin and evolution of the early Solar System. Recent studies have challenged the traditional idea that the Trojans were formed in-situ and proposed that they were originally formed in the trans-Neptunian region and were later captured by Jupiter. It is now understood that Trojans are among the most primitive objects in the vicinity of the inner Solar System. NASA’s Lucy mission is set to explore a number of Trojans starting 2027. With this experiment, we will conduct a characterization survey of both the L4 and L5 Jupiter Trojans using ZTF, as they reach opposition in October 2024 and February 2025, respectively. The goal of this experiment is to constrain the rotation and phase curves of the Trojans as well as the coupling of their colors.

Lead: Christoffer Fremling (Caltech)

Desciption: We aim to perform an unbiased classification survey of all transients down to a specific limiting magnitude - similar to the Bright Transient Survey (BTS), but using the full three-band (g/r/i) abilities of ZTF and down to a deeper magnitude than is normally possible (at least 19.5 mag) and at a slightly higher cadence (1 night instead of 2). The aim is to quantify what we are missing in the fainter, faster, and redder regimes where BTS is not complete. Producing a complete sample in these regimes, even if relatively small compared to BTS itself, will aid photometric classifiers for the Vera Rubin era and to utilize the tens of thousands of unclassified extragalactic transients in the ZTF archive.

Lead: Nabeel Rehemtulla (Northwestern University)

Desciption: This ZTF experiment is designed to identify infant Type II SNe suitable for UV observations with HST through the “Flexible Thursdays” program. The Flexible Thursdays program was recently introduced to allow for much quicker response to time of opportunity triggers. This is particularly useful for studying young ( more than 1 week after explosion) Type II SNe in the UV, where one can briefly glean information on the local circumstellar environment and the red supergiant progenitor. In terms of ZTF operations, this experiment is minimally disruptive as it is essentially a wider/faster version of BTS observing. We will prioritize obtaining two 30 second exposures (1 in g, 1 in r) per field per night over extragalactic fields.

Lead: Zach Vanderbosch (Caltech)

Desciption: The ZTF Galactic science working group is undertaking a second 3-night experiment from UT July 1 - 3 to perform all-night deep drilling of three separate galactic-plane fields, one per night. Similar to our first experiment in January, the goal of these observations will be to both detect and resolve stellar variability on all timescales covered by the baseline of a full night (about 6.2 hr in early July), although this time in regions of significantly higher on-sky stellar densities compared to our Galactic anti-center fields from the first experiment. The near-IR Gattini-IR instrument will also observe the same sky areas each night, cycling through four fields to obtain continuous J-band light curves down to m~15 AB mag depth with one eighth the ZTF cadence. We will also attempt to perform overlapping observations of SDSS-V fields to obtain concurrent time-series photometric and spectroscopic survey data.

Lead: Anna Ho (Cornell)

Desciption:In anticipation of ULTRASAT (launch expected in 2026), we propose to obtain near-continuous imaging of the northern ULTRASAT high-cadence field, and to autonomously trigger Swift on young and fast-brightening transients. Our goals are to (1) explore the minute-timescale optical sky by identifying transient and variable sources in the region, and (2) do a technical demonstration that Swift can autonomously observe a young optically-discovered transient.

Lead: Christoffer Fremling (Caltech)

Desciption: We aim for an experiment that is basically the Bright Transient Survey (BTS), but using 100% of the telescope time for three full nights instead of the usual 50%. We want to coordinate this with spectroscopic resources to be able to classify virtually all new transients (down to 19.5 mag) discovered during this dedicated effort. The aim is to quantify what we are missing at the fainter end where BTS is not complete, which will aid photometric classifiers that are needed both in the Vera Rubin era, but also to harvest the many tens of thousands of extragalactic transients in the ZTF archive for which we did not get spectroscopic classifications.

Lead: Yujing Qin (Caltech)

Desciption: The experiment aims to conduct a deep, snapshot-style survey of nearby galaxy overdensities including the Virgo, Coma, Hercules, and the Shapley supercluster to characterize the population properties of optical transients – their brightness, rising or fading rates, and host galaxy properties. The fewer number of pointings enables a longer exposure time, allowing for deeper sensitivity limits than the public survey. A catalog of transient candidates will be made available to the community.

Lead: Tomas Ahumada (Caltech)

The goal of this experiment is to exploit the usage of a DECam in tandem with ZTF and discover fast evolving transients in the overlapping area of these telescopes. With DECam, we will cover the same region on March 1st with one 30 sec g-band exposure and push candidates to Fritz. We plan to scan in real time and send interesting transients to other facilities for follow up.

Lead: Zach Vanderbosch (Caltech)

The ZTF Galactic science working group is undertaking a 3-night experiment to perform nearly all-night deep drilling of three individual fields, one per night. The goal of these observations will be to both detect and resolve stellar variability on all timescales covered by the baseline of a full night (~11 hr in January), and to assess the completeness of SCoPE periodicty detections in regions of different stellar densities by comparing SCoPE periods with periods detected within the experimental observations. The goals prompting the observations of the secondary fields are to to assess the feasibility and scientific return of near-simultaneous photometric and spectroscopic survey observations and to detect new variable sources within the COSMOS field, which is also planned for deep-drilling observations with Rubin-LSST.

Lead: Tomas Ahumada (Caltech)

The first pilot extragalactic ZTF experiment was carried out in Dec 2023. Distinct from regular ZTF operations, this experiment emphasizes densely sampled, intranight observations with deeper exposure, aiming at optimizing the detection efficiency of fast-evolving or newly emerging optical transients. Details and initial results were posted in this Astro Note.