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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').

18802 results found.

  1. GRB 240516A ATCA radio observations
  2. IPN triangulation of GRB 240514B (short)
  3. Konus-Wind detection of GRB 240513A
  4. GRB 240516A: Swift-XRT refined Analysis
  5. GRB 240511A: Observations from GTC/OSIRIS+
  6. GRB 240516A: GOTO optical upper limit
  7. LIGO/Virgo/KAGRA S240422ed: GRID non-detection and upper limits
  8. Fermi trigger No 737523389: Global MASTER-Net observations report
  9. GRB 240516A: Swift detection of a burst
  10. GRB 240511A: radio detection of afterglow candidate
  11. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  12. GRB 240513A: Swift-XRT observations
  13. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  14. GRB 240514D: AstroSat CZTI detection
  15. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  16. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  17. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  18. GRB 240511A: J-band observations with WINTER
  19. GRB 240511A: Enhanced Swift-XRT position
  20. GRB 240511A : MITSuME Akeno optical upper limits
  21. LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
  22. GRB 240511A: Swift-XRT refined Analysis
  23. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  24. GRB 240511A: Swift detection of a burst
  25. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  27. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  28. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  29. EP240506a: Xinglong optical upper limit
  30. EP240506a: Archival radio searching
  31. EP240506a: TRT 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 S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  40. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  41. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  42. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  43. GW170817: VLA observations at ~5.5 yrs since merger
  44. GRB 240503A: AstroSat CZTI detection
  45. GRB 240415A 1.3m DFOT Optical upper limit
  46. GRB 240502C: GOTO possible optical counterpart candidates
  47. LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
  48. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  49. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  50. GRB 240501B: AstroSat CZTI detection
  51. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  53. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  54. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  55. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  56. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  57. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  59. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  60. EP240426b: AST3-2 optical upper limit
  61. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  62. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  63. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  64. EP240426b: EP-WXT detection of a new fast X-ray transient
  65. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  66. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  67. GRB 240426A: AstroSat CZTI detection
  68. XMM-Newton observation of EP240426a
  69. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  70. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  71. GRB 240414A: NOEMA detection
  72. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  73. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  74. EP240426a: GMG optical upper limit
  75. LVK S240422ed: Further Swift-XRT followup of three sources
  76. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  78. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  79. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  80. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  81. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  82. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  83. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  84. GRB 240422A: Glowbug gamma-ray detection
  85. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  86. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  87. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  88. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  89. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  90. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  91. LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts
  92. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  93. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  94. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  95. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  96. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  97. LIGO/Virgo/KAGRA S240422ed: Potential Magellan candidates from GCN 36263 are unrelated.
  98. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  99. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  100. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart

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