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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').

22244 results found.

  1. GRB 240511A: Swift detection of a burst
  2. LIGO/Virgo/KAGRA S240511i: Updated Sky localization
  3. Fermi trigger No 737111207: Global MASTER-Net observations report
  4. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  6. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  7. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  8. EP240506a: Xinglong optical upper limit
  9. GRB 240504A: Fermi GBM Observation
  10. EP240506a: Archival radio searching
  11. EP240506a: TRT optical upper limit
  12. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  13. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  14. EP240506a: Optical upper limit with Kinder observations
  15. IPN triangulation of GRB 240504A
  16. GRB 240502A: 1.3m DFOT Optical upper limit
  17. EP240506a: EP-WXT detection of a new fast X-ray transient
  18. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  20. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  21. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  22. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  23. Fermi trigger No 736461232: Global MASTER-Net observations report
  24. GW170817: VLA observations at ~5.5 yrs since merger
  25. GRB 240504A: BALROG localization (Fermi Trigger 736492377 / GRB 240504217)
  26. GRB 240502A: Fermi GBM Observation
  27. GRB 240415A 1.3m DFOT Optical upper limit
  28. LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
  29. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  30. GRB 240426A: VZLUSAT-2 detection
  31. GRB 240425A: VZLUSAT-2 detection
  32. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  33. GRB 240501B: AstroSat CZTI detection
  34. GRB 240501A: Fermi GBM Final Real-time Localization
  35. GRB 240408B: VZLUSAT-2 detection
  36. GRB 240407A: VZLUSAT-2 detection
  37. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  38. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  39. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  40. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  41. Additional DECam GW-MMADS Candidates from three nights of observations
  42. Fermi-LAT gamma-ray observations of IceCube-240424A
  43. LIGO/Virgo/KAGRA S240426s: Updated Sky localization
  44. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  45. LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
  46. LIGO/Virgo/KAGRA S240428dr: Updated Sky localization
  47. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  48. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  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 S240422ed: Swift XRT observation of EP240426a
  54. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  55. EP240426b: EP-WXT detection of a new fast X-ray transient
  56. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  57. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  58. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  59. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  60. GRB 240426A: AstroSat CZTI detection
  61. XMM-Newton observation of EP240426a
  62. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  63. GRB 240414A: NOEMA detection
  64. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  65. EP240426a: GMG optical upper limit
  66. LVK S240422ed: Further Swift-XRT followup of three sources
  67. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  68. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  69. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  70. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  71. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  72. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  73. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  74. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  75. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  76. LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations
  77. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  78. GRB 240419B: Swift-BAT refined analysis
  79. GRB 240421B: Swift-BAT refined analysis
  80. GRB 240422A: Glowbug gamma-ray detection
  81. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  82. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  83. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  84. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  85. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  86. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  87. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  88. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  89. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  90. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  91. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  92. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  93. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  94. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  95. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  96. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  97. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  98. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  99. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  100. GRB 240419A: Swift-BAT refined analysis

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