Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').

17298 results found.

  1. GRB 240516A: Swift detection of a burst
  2. GRB 240511A: radio detection of afterglow candidate
  3. GRB 240514B: GOTO candidate optical counterpart
  4. GRB 240514B: GRBAlpha detection
  5. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  6. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  7. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  8. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  9. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  10. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  11. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  12. LAT GRB240513.31: Global MASTER-Net observations report
  13. GRB 240513A: Fermi-LAT detection
  14. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  15. GRB 240511A: Swift-BAT refined analysis
  16. GRB 240513A: AstroSat CZTI detection
  17. GRB 240511A: J-band observations with WINTER
  18. GRB 240511A: Enhanced Swift-XRT position
  19. GRB 240511A : MITSuME Akeno optical upper limits
  20. LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
  21. GRB 240511A: Swift-XRT refined Analysis
  22. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  23. GRB 240511A: Swift detection of a burst
  24. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  26. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  27. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  28. EP240506a: Xinglong optical upper limit
  29. EP240506a: Archival radio searching
  30. EP240506a: TRT optical upper limit
  31. EP240506a: BOOTES Network optical upper limit
  32. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  33. EP240506a: Optical upper limit with Kinder observations
  34. IPN triangulation of GRB 240504A
  35. GRB 240502A: 1.3m DFOT Optical upper limit
  36. EP240506a: EP-WXT detection of a new fast X-ray transient
  37. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  38. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  39. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  40. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  41. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  42. GW170817: VLA observations at ~5.5 yrs since merger
  43. GRB 240503A: AstroSat CZTI detection
  44. GRB 240502A: GOTO optical upper limit
  45. GRB 240415A 1.3m DFOT Optical upper limit
  46. LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
  47. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  48. GRB 240501B: GRBAlpha detection
  49. GRB 240430A: GRBAlpha detection
  50. LIGO/Virgo/KAGRA S240422ed: Host redshifts of AT2024hfq, AT2024hfu, and AT2024hmo from DBSP
  51. GRB 240426A: VZLUSAT-2 detection
  52. GRB 240425A: VZLUSAT-2 detection
  53. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  54. GRB 240501B: AstroSat CZTI detection
  55. GRB 240408B: VZLUSAT-2 detection
  56. GRB 240407A: VZLUSAT-2 detection
  57. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  59. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  61. GRB 240425A: GRBAlpha detection
  62. Fermi-LAT gamma-ray observations of IceCube-240424A
  63. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  64. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  65. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  67. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  68. EP240426b: AST3-2 optical upper limit
  69. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  70. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  71. EP240426b: EP-WXT detection of a new fast X-ray transient
  72. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  73. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  74. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  75. EP240426a: YAHPT optical upper limit
  76. XMM-Newton observation of EP240426a
  77. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  78. GRB 240414A: NOEMA detection
  79. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  80. EP240426a: GMG optical upper limit
  81. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  83. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  84. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  85. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  86. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  87. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  88. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  89. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  90. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  91. GRB 240422A: Glowbug gamma-ray detection
  92. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  93. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  94. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  95. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  96. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  97. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  98. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  99. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  100. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov