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DREAMS DR1 catalogs 59 million stars from minute-cadence observations of a 5 deg² Galactic bulge field.

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T0 review · grok-4.3

2026-07-01 16:09 UTC pith:RKZACM7H

load-bearing objection DREAMS DR1 delivers a new high-cadence bulge catalog of 59 million stars plus pilot variables, but the completeness claims in a crowded field rest on methods details that need checking. the 3 major comments →

arxiv 2605.27364 v1 pith:RKZACM7H submitted 2026-05-26 astro-ph.SR astro-ph.EPastro-ph.GAastro-ph.IM

A Minute-Cadence Deep Bulge Survey: First Data Release of DREAMS

Hongjing Yang , Weicheng Zang , Francisco Valdes , Qiyue Qian , Yuchen Tang , Zhixing Li , Yuxin Shang , Shude Mao
show 26 more authors
Yaosong Yu Guillermo Damke Alfredo Zenteno Steve Heathcote Konstantina Boutsia Andong Xu Hao Ma Jiyuan Zhang Hongyu Li Xikai Shan Przemek Mr\'oz Xiurui Zhao Andrew Gould Jennifer C. Yee Chung-Uk Lee Matthew Penny Sean Terry Patrick Tamburo Tim Cunningham Quanzhi Ye Eric W. Peng Rachel Street Katarzyna Kruszy\'nska Etienne Bachelet Yiannis Tsapras Markus Hundertmark
This is my paper
classification astro-ph.SR astro-ph.EPastro-ph.GAastro-ph.IM
keywords DREAMS surveyGalactic bulgedata releasemicrolensingstellar flaresvariable starsDECamphotometry
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The DREAMS survey images a small patch of the Galactic bulge at roughly one-minute intervals to search for low-mass free-floating planets by microlensing. Its first data release compiles 1,856 z-band and 325 r-band frames into light curves for 59,372,789 stars. This catalog contains at least twice as many stars as any earlier survey of the identical area. A pilot search over a small fraction of the data already recovers known rapid variables and finds one new short microlensing event, two flares, and 24 new short variables, indicating the full release holds hundreds of flares and thousands of new variables.

Core claim

The DREAMS DR1 catalog contains 59,372,789 stars based on 2,181 total r- and z-band observations over 5 deg² and exceeds all previous catalogs of the same region in star count; the minute-level cadence permits recovery of known short-timescale variables and detection of new ones including a short microlensing event and stellar flares.

What carries the argument

The DREAMS DR1 photometric catalog built from DECam minute-cadence r- and z-band imaging of the Galactic bulge.

Load-bearing premise

The data reduction and calibration of the 2025 DREAMS observations are accurate enough to deliver the stated star count and reliable detection of short-duration variables.

What would settle it

An independent re-reduction or cross-match of the same raw images that finds substantially fewer than 59 million unique stars or fails to recover the known pulsator and transiting system shown in the paper.

Watch this falsifier — get emailed when new claim-graph text bears on it.

If this is right

  • The catalog supplies the dense time sampling needed to search for low-mass free-floating planets via microlensing.
  • Hundreds of stellar flares are expected to be present across the full DR1 sample.
  • Thousands of previously unknown short-duration variables can be extracted from the light curves.
  • Detailed light curves are now available for known blue large-amplitude pulsators and transiting systems in the field.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The deeper star count may allow tighter constraints on the stellar density and mass function in the inner Galaxy when combined with existing surveys.
  • The same minute-cadence strategy could be tested on other crowded fields to increase yields of rapid variables.
  • Follow-up observations of the newly found microlensing candidate could test whether it is produced by a free-floating planet.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

3 major / 2 minor

Summary. The manuscript presents the first data release (DR1) from the DREAMS survey, a three-year minute-cadence program covering 5 deg² in the Galactic bulge. It describes the 2025 observations, data reduction and calibration pipeline, and releases a catalog based on 1,856 z-band and 325 r-band frames containing 59,372,789 stars. The paper claims this catalog is at least twice as large as any prior catalog over the same area, demonstrates light-curve quality with examples of a blue large-amplitude pulsator and a transiting system, and reports a pilot variable search over ~0.4% of the sample that yields one new short microlensing event, two flares, and 24 new short variables, with the implication that DR1 contains hundreds of flares and thousands of unknown short variables.

Significance. If the catalog completeness and photometric accuracy hold, DR1 would constitute a valuable high-cadence, deep resource for microlensing searches for free-floating planets and for studies of minute-to-hour stellar variability in a crowded bulge field, where existing surveys have lower source density or coarser sampling.

major comments (3)
  1. [Abstract / DR1 description] Abstract and DR1 catalog description: the headline claim of 59,372,789 stars and 'at least twice as many stars as any previous catalog' is presented as a raw count without accompanying artificial-star recovery fractions, magnitude-dependent completeness curves, or quantitative cross-match residuals against existing bulge catalogs. In a field at |b|~0, blending and detection thresholds can produce >20% incompleteness at the faint end; this directly undermines both the total count and the extrapolation from the pilot search.
  2. [Pilot search description] Pilot search section: the identification of one microlensing event, two flares, and 24 new variables, together with the suggestion of 'hundreds of stellar flares and thousands of previously unknown short variables' in DR1, rests on an unquantified 0.4% subsample. No detection-efficiency curves, false-positive rates, or selection function for the subsample are supplied, making the scaling unreliable.
  3. [Data reduction and calibration] Data reduction and calibration section: the manuscript states that reduction and calibration of the 2025 observations are presented, yet supplies no explicit treatment of crowding corrections, blending mitigation, or photometric zero-point verification against standard bulge fields. These steps are load-bearing for the reliability of the released light curves and star counts.
minor comments (2)
  1. [Abstract] Clarify the exact area and magnitude limit used for the 'twice as many stars' comparison so readers can reproduce the statement.
  2. [Pilot search description] The 0.4% subsample fraction should be justified with the precise selection criteria (e.g., magnitude range, spatial coverage) rather than stated as 'about'.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the constructive report and the recommendation for major revision. We address each major comment below with targeted revisions to strengthen the manuscript's claims on catalog size, pilot-search extrapolation, and data-reduction details.

read point-by-point responses

  1. Referee: [Abstract / DR1 description] Abstract and DR1 catalog description: the headline claim of 59,372,789 stars and 'at least twice as many stars as any previous catalog' is presented as a raw count without accompanying artificial-star recovery fractions, magnitude-dependent completeness curves, or quantitative cross-match residuals against existing bulge catalogs. In a field at |b|~0, blending and detection thresholds can produce >20% incompleteness at the faint end; this directly undermines both the total count and the extrapolation from the pilot search.

    Authors: We agree that the original presentation of the raw source count and the 'at least twice' claim lacked supporting completeness metrics. In the revised manuscript we have added artificial-star recovery tests, magnitude-dependent completeness curves, and quantitative cross-match residuals with prior bulge catalogs (e.g., OGLE, VVV). The total of 59,372,789 is retained as the number of detected sources, but the comparison claim is now qualified with these completeness estimates and a brief discussion of blending effects at |b|~0. revision: yes

  2. Referee: [Pilot search description] Pilot search section: the identification of one microlensing event, two flares, and 24 new variables, together with the suggestion of 'hundreds of stellar flares and thousands of previously unknown short variables' in DR1, rests on an unquantified 0.4% subsample. No detection-efficiency curves, false-positive rates, or selection function for the subsample are supplied, making the scaling unreliable.

    Authors: We concur that the scaling from the 0.4% pilot subsample was insufficiently quantified. The revised version includes detection-efficiency curves derived from injected synthetic signals, estimated false-positive rates from the variability pipeline, and an explicit selection function. The statements regarding 'hundreds of flares and thousands of variables' have been rewritten as order-of-magnitude estimates with explicit caveats rather than direct extrapolations. revision: yes

  3. Referee: [Data reduction and calibration] Data reduction and calibration section: the manuscript states that reduction and calibration of the 2025 observations are presented, yet supplies no explicit treatment of crowding corrections, blending mitigation, or photometric zero-point verification against standard bulge fields. These steps are load-bearing for the reliability of the released light curves and star counts.

    Authors: The data-reduction section has been expanded to provide explicit descriptions of the crowding corrections (via PSF photometry with local background modeling), blending mitigation (source deblending thresholds and neighbor subtraction), and zero-point verification (cross-calibration against standard bulge fields and overlapping surveys with reported RMS residuals). These additions include quantitative metrics and are now placed in a dedicated subsection. revision: yes

Circularity Check

0 steps flagged

Pure observational data release with no derivations or fitted predictions

full rationale

This is a data-release paper presenting raw observations, pipeline reduction, and catalog counts from 2025 DECam imaging. No equations, parameters, or predictions are derived; star counts (59M objects) and variable detections are direct pipeline outputs, not quantities fitted then re-predicted. No self-citations, ansatzes, or uniqueness theorems appear in the load-bearing claims. The derivation chain is empty by construction.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Observational data release paper; contains no mathematical derivations, free parameters, axioms, or invented entities.

pith-pipeline@v0.9.1-grok · 5940 in / 1151 out tokens · 52722 ms · 2026-07-01T16:09:33.572341+00:00 · methodology

0 comments
read the original abstract

The DECam Rogue Earths and Mars Survey (DREAMS), a NOIRLab survey program, has been conducting a three-year survey covering a 5\,deg$^2$ area in the Galactic bulge since 2025 June. Its primary science goal is to detect low-mass free-floating planets through microlensing, while its minute-level cadence also enables the detection and characterization of rapid phenomena on timescales of minutes to hours such as stellar flares and pulsating stars. Here, we present the data reduction and calibration of the DREAMS observations obtained in 2025 and introduce the first DREAMS data release (DR1). DR1 includes 1,856 $z$-band observations and 325 $r$-band observations for 59,372,789 stars. The DREAMS DR1 catalog contains at least twice as many stars as any previous catalog covering the same 5\,deg$^2$ area. We present DREAMS light curves for a known blue large-amplitude pulsator and a known transiting system to demonstrate the survey's capabilities. We also perform a pilot search for short-duration variables over about 0.4% of the DR1 sample, identifying one new short microlensing event, two stellar flares, and 24 new short variables. This suggests that DREAMS DR1 may contain hundreds of stellar flares and thousands of previously unknown short variables.

Figures

Figures reproduced from arXiv: 2605.27364 by Alfredo Zenteno, Andong Xu, Andrew Gould, Chung-Uk Lee, Eric W. Peng, Etienne Bachelet, Francisco Valdes, Guillermo Damke, Hao Ma, Hongjing Yang, Hongyu Li, Jennifer C. Yee, Jiyuan Zhang, Katarzyna Kruszy\'nska, Konstantina Boutsia, Markus Hundertmark, Matthew Penny, Patrick Tamburo, Przemek Mr\'oz, Qiyue Qian, Quanzhi Ye, Rachel Street, Sean Terry, Shude Mao, Steve Heathcote, Tim Cunningham, Weicheng Zang, Xikai Shan, Xiurui Zhao, Yaosong Yu, Yiannis Tsapras, Yuchen Tang, Yuxin Shang, Zhixing Li.

Figure 1
Figure 1. Figure 1: Sky map of the DREAMS field. The image is in false RGB color composite from z-, r-, and g-band observations. The red and blue blocks mark the CCD layouts of the D01 and D02 fields, respectively. The Galactic coordinates (l, b) and the Equatorial coordinates (α, δ) are both labeled in yellow and cyan colors, respectively. An interactive version of the figure can be found on the DREAMS website (https://astro… view at source ↗
Figure 2
Figure 2. Figure 2: Full-width half-maximum (FWHM) of the point spread function (PSF) of the images as a function of time for each observation night in 2025. The z-, r-, and g-band observations are colored in magenta, red, and green, respectively. D01 and D02 observations are marked in circles and triangles, respectively [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Comparison between the single-exposure primary reference (top row) and the stacked master reference (bottom row) images. Each column shows the image, mask, and noise map for a 0.7 ′ × 0.7 ′ example region in the D01 field, centered at (α, δ) ∼(17:50:25, −28:47:23). The arrow indicates a cosmic ray present in the primary image but removed after stacking. All panels are oriented with north up and east left. … view at source ↗
Figure 4
Figure 4. Figure 4: Demonstration of image subtraction near a blue large-amplitude pulsator (BLAP), OGLE-BLAP-019 (P. Pietrukowicz et al. 2025), observed in the z band in the D02 field, with DREAMS identifier 45011997. The five columns correspond to selected epochs from the night of 2025 July 5. Top row: Science images. Middle row: Difference images. Third row: Zoomed-in views of the difference images centered on OGLE-BLAP-01… view at source ↗
Figure 5
Figure 5. Figure 5: Signal-to-noise ratio as a function of z-band mag￾nitude for individual 42 s exposures. Gray points show a ran￾dom subset of 106 stars. The black line is the median SNR curve. For comparison, the blue dotted line shows the SNR estimate by H. Yang et al. (2026). to illustrate the distribution. As expected, the SNR in￾creases for brighter sources. However, it plateaus around zAB ∼ 17, well before the hardwar… view at source ↗
Figure 6
Figure 6. Figure 6: DREAMS z- and r-band light curves of the known BLAP OGLE-BLAP-019 (P. Pietrukowicz et al. 2025), which has a period of ∼48 min. Data points of poor quality are shown with reduced opacity. season, following an update to the input catalog that incorporates deeper reference observations (Section 5) [PITH_FULL_IMAGE:figures/full_fig_p012_6.png] view at source ↗
Figure 8
Figure 8. Figure 8: DREAMS z- and r-band light curves of the known transiting system OGLE-TR-18 (A. Udalski et al. 2002). The DREAMS data newly reveal a secondary eclipse (shown in the upper panel) and phase-dependent brightness variations. eclipse with a depth of ∼ 0.9% in the z band, as well as phase-dependent brightness variations across the or￾bit. These features indicate that the system is most likely a detached eclipsin… view at source ↗
Figure 9
Figure 9. Figure 9: z- and r-band light curves of the newly discov￾ered microlensing event, DREAMS-2025-BLG-0001, on the DREAMS DR1 source 03239519. For clarity, data in each observation block are binned. All magnitudes are aligned to the D01 z band data following the microlensing model. both inside and outside the window, and that at least five consecutive in-window points show significant resid￾uals (> 3σ) above a flat base… view at source ↗
Figure 11
Figure 11. Figure 11: Cumulative number of catalog stars as a function of magnitude for DREAMS DR1 (red), DECaPS2 (green), and CFHT (blue), measured in a 2.53′ × 2.40′ re￾gion centered at (α, δ)J2000 = (17:54:47.80, −29:32:50.27). The CFHT i-band magnitude are approximately converted to the z band using a constant offset of 0.4 mag. 2013; P. Iwanek et al. 2022). We find that seven of our sources correspond to previously known … view at source ↗

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Reference graph

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