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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').

22269 results found.

  1. GRB 240511A: radio detection of afterglow candidate
  2. MAXI GRB240514.78: Global MASTER-Net observations report
  3. GRB 240514E: MAXI/GSC detection of a probable afterglow
  4. LIGO/Virgo/KAGRA S240514x: Updated Sky localization
  5. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  6. GRB 240513A: Fermi GBM observation
  7. GRB 240513A: Swift-XRT observations
  8. LIGO/Virgo/KAGRA S240513ei: Updated Sky localization
  9. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  11. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  12. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  13. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  14. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  15. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  16. GRB 240511A: Fermi GBM Observation
  17. GRB 240511A: Swift-BAT refined analysis
  18. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  19. GRB 240511A: J-band observations with WINTER
  20. Fermi trigger No 737247400: Global MASTER-Net observations report
  21. Fermi trigger No 737168073: Global MASTER-Net observations report
  22. GRB 240511A: Enhanced Swift-XRT position
  23. GRB 240511A : MITSuME Akeno optical upper limits
  24. LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
  25. GRB 240511A: Swift-XRT refined Analysis
  26. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  27. GRB 240511A: Swift detection of a burst
  28. LIGO/Virgo/KAGRA S240511i: Updated Sky localization
  29. Fermi trigger No 737111207: Global MASTER-Net observations report
  30. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  32. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  33. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  34. EP240506a: Xinglong optical upper limit
  35. GRB 240504A: Fermi GBM Observation
  36. EP240506a: Archival radio searching
  37. EP240506a: TRT optical upper limit
  38. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  39. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  40. EP240506a: Optical upper limit with Kinder observations
  41. IPN triangulation of GRB 240504A
  42. GRB 240502A: 1.3m DFOT Optical upper limit
  43. EP240506a: EP-WXT detection of a new fast X-ray transient
  44. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  45. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  46. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  47. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  48. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  49. Fermi trigger No 736461232: Global MASTER-Net observations report
  50. GW170817: VLA observations at ~5.5 yrs since merger
  51. GRB 240504A: BALROG localization (Fermi Trigger 736492377 / GRB 240504217)
  52. GRB 240502A: Fermi GBM Observation
  53. GRB 240415A 1.3m DFOT Optical upper limit
  54. LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
  55. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  56. GRB 240426A: VZLUSAT-2 detection
  57. GRB 240425A: VZLUSAT-2 detection
  58. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  59. GRB 240501B: AstroSat CZTI detection
  60. GRB 240501A: Fermi GBM Final Real-time Localization
  61. GRB 240408B: VZLUSAT-2 detection
  62. GRB 240407A: VZLUSAT-2 detection
  63. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  64. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  65. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  67. Additional DECam GW-MMADS Candidates from three nights of observations
  68. Fermi-LAT gamma-ray observations of IceCube-240424A
  69. LIGO/Virgo/KAGRA S240426s: Updated Sky localization
  70. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  71. LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
  72. LIGO/Virgo/KAGRA S240428dr: Updated Sky localization
  73. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  74. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  75. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  76. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  77. EP240426b: AST3-2 optical upper limit
  78. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  79. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  80. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  81. EP240426b: EP-WXT detection of a new fast X-ray transient
  82. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  83. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  84. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  85. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  86. GRB 240426A: AstroSat CZTI detection
  87. XMM-Newton observation of EP240426a
  88. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  89. GRB 240414A: NOEMA detection
  90. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  91. EP240426a: GMG optical upper limit
  92. LVK S240422ed: Further Swift-XRT followup of three sources
  93. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  94. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  95. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  96. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  97. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  98. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  99. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  100. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations

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