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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').

16007 results found.

  1. IPN triangulation of GRB 240514B (short)
  2. GRB 240516A: AstroSat CZTI detection
  3. GRB 240514E: A possible candidate BD-21 1074
  4. GRB 240511A: Observations from GTC/OSIRIS+
  5. LIGO/Virgo/KAGRA S240422ed: GRID non-detection and upper limits
  6. GRB 240516A: Swift detection of a burst
  7. GRB 240511A: radio detection of afterglow candidate
  8. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  9. GRB 240513A: Swift-XRT observations
  10. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  11. GRB 240514D: AstroSat CZTI detection
  12. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  13. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  14. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  15. GRB 240513A: AstroSat CZTI detection
  16. GRB 240511A: J-band observations with WINTER
  17. GRB 240511A: Enhanced Swift-XRT position
  18. GRB 240511A : MITSuME Akeno optical upper limits
  19. GRB 240511A: Swift-XRT refined Analysis
  20. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  21. GRB 240511A: Swift detection of a burst
  22. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  24. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  25. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  26. EP240506a: Xinglong optical upper limit
  27. EP240506a: Archival radio searching
  28. EP240506a: TRT optical upper limit
  29. EP240506a: BOOTES Network optical upper limit
  30. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  31. EP240506a: Optical upper limit with Kinder observations
  32. IPN triangulation of GRB 240504A
  33. GRB 240502A: 1.3m DFOT Optical upper limit
  34. EP240506a: EP-WXT detection of a new fast X-ray transient
  35. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  37. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  38. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  39. GW170817: VLA observations at ~5.5 yrs since merger
  40. GRB 240504A: Fermi GBM Final Real-time Localization
  41. GRB 240415A 1.3m DFOT Optical upper limit
  42. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  43. GRB 240501B: AstroSat CZTI detection
  44. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  45. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  46. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  47. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  48. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  49. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  50. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  51. EP240426b: AST3-2 optical upper limit
  52. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  53. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  54. EP240426b: EP-WXT detection of a new fast X-ray transient
  55. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  56. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  57. GRB 240426A: AstroSat CZTI detection
  58. XMM-Newton observation of EP240426a
  59. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  61. GRB 240414A: NOEMA detection
  62. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  63. EP240426a: GMG optical upper limit
  64. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  66. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  67. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  68. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  69. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  70. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  71. GRB 240421B: Swift-BAT refined analysis
  72. GRB 240422A: Glowbug gamma-ray detection
  73. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  74. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  75. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  76. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  77. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  78. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  79. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  80. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  81. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  82. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  83. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  84. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  85. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  86. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  87. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  88. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  89. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  90. LXT240402A/GRB240402B: Chandra X-ray detection
  91. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  92. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  93. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  94. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  95. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  96. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  97. GRB 240421A: Glowbug gamma-ray detection
  98. GRB 240414A: radio detection with the VLA
  99. GRB 240414A: AMI-LA radio observations
  100. GRB 240414A: LBT optical detection

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