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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').

15494 results found.

  1. GRB 240511A: Swift detection of a burst
  2. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  3. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  4. EP240506a: Xinglong optical upper limit
  5. EP240506a: Archival radio searching
  6. EP240506a: TRT optical upper limit
  7. EP240506a: Optical upper limit with Kinder observations
  8. IPN triangulation of GRB 240504A
  9. GRB 240502A: 1.3m DFOT Optical upper limit
  10. EP240506a: EP-WXT detection of a new fast X-ray transient
  11. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  12. GW170817: VLA observations at ~5.5 yrs since merger
  13. GRB 240415A 1.3m DFOT Optical upper limit
  14. Fermi GRB 240502B: Global MASTER-Net observations report
  15. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  16. X-ray transient EP240414a: Detection of associated supernova
  17. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  18. Fermi-LAT gamma-ray observations of IceCube-240424A
  19. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  20. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  21. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  22. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  23. EP240426b: AST3-2 optical upper limit
  24. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  25. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  26. EP240426b: EP-WXT detection of a new fast X-ray transient
  27. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  28. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  29. XMM-Newton observation of EP240426a
  30. GRB 240414A: NOEMA detection
  31. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  32. EP240426a: GMG optical upper limit
  33. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  34. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  35. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  36. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  37. GRB 240422A: Glowbug gamma-ray detection
  38. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  39. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  40. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  41. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  42. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  43. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  44. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  45. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  46. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  47. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  48. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  49. LIGO/Virgo/KAGRA S240422ed: LAST optical observations
  50. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  51. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  52. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  53. LXT240402A/GRB240402B: Chandra X-ray detection
  54. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  55. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  56. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  57. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  58. GRB 240421A: Glowbug gamma-ray detection
  59. GRB 240414A: radio detection with the VLA
  60. Fermi-LAT gamma-ray observations of IceCube-240419A
  61. GRB 240414A: AMI-LA radio observations
  62. GRB 240414A: LBT optical detection
  63. GRB 240419B : MITSuME Akeno optical upper limits
  64. GRB 240421B: AstroSat CZTI detection
  65. GRB240421B: Zadko Observations
  66. GRB 240421B: Fermi GBM Observation
  67. GRB 240421B: J-band upper limits from WINTER
  68. GRB 240421B: Swift/UVOT Upper Limits
  69. GRB 240421B: Enhanced Swift-XRT position
  70. EP240417a: no counterpart detection by SOAR
  71. EP240420a: Xinglong decaying optical counterpart
  72. GRB 240421B: Swift detection of a burst
  73. EP240420a: Nanshan optical counterpart observations
  74. EP240420a: GWAC-F50A optical upper limit
  75. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  76. EP240420a: NOT optical counterpart candidate and potential host
  77. Fermi trigger No 735280430: Global MASTER-Net observations report
  78. GRB240419A: Skynet Optical Afterglow Analysis
  79. GRB240418A - Candidate afterglow from NIRES
  80. GRB 240419B: Swift/UVOT Upper Limits
  81. EP240420a: EP-WXT detection of a fast X-ray transient
  82. GRB 240419A: Swift/UVOT Upper Limits
  83. GRB 240419B: optical afterglow from the NOT
  84. GRB 240419B: Enhanced Swift-XRT position
  85. GRB 240418A: Swift/UVOT Upper Limits
  86. GRB 240419A: REM NIR afterglow detection
  87. GRB 240418A: Swift-XRT refined Analysis
  88. GRB 240419B: Swift detection of a burst
  89. GRB 240411B: Swift/UVOT Detection
  90. GRB 240419A: VLT optical afterglow detection
  91. GRB 240419A: Enhanced Swift-XRT position
  92. EP240416a: J-band observations with WINTER
  93. EP240414a: GMG observation
  94. GRB 240419A: Swift detection of a burst
  95. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  96. GRB 240418A: NOT optical upper limits
  97. GRB 240418A: Enhanced Swift-XRT position
  98. GRB 240418A: AKO Upper Limit
  99. GRB 240418A: Swift detection of a burst
  100. EP240417a: EP-WXT detection of a fast X-ray transient

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